diff --git a/wp-admin/includes/ajax-actions.php b/wp-admin/includes/ajax-actions.php
index 5a6c767b5e..3f39fe203f 100644
--- a/wp-admin/includes/ajax-actions.php
+++ b/wp-admin/includes/ajax-actions.php
@@ -331,7 +331,7 @@ function wp_ajax_autocomplete_user() {
 }
 
 /**
- * Handles AJAX requests for community events
+ * Handles Ajax requests for community events
  *
  * @since 4.8.0
  */
diff --git a/wp-admin/includes/class-wp-site-health.php b/wp-admin/includes/class-wp-site-health.php
index 3beb111bb4..4d337f9a5d 100644
--- a/wp-admin/includes/class-wp-site-health.php
+++ b/wp-admin/includes/class-wp-site-health.php
@@ -178,8 +178,8 @@ class WP_Site_Health {
 	/**
 	 * Run the SQL version checks.
 	 *
-	 * These values are used in later tests, but the part of preparing them is more easily managed early
-	 * in the class for ease of access and discovery.
+	 * These values are used in later tests, but the part of preparing them is more easily managed
+	 * early in the class for ease of access and discovery.
 	 *
 	 * @since 5.2.0
 	 *
@@ -212,11 +212,11 @@ class WP_Site_Health {
 	/**
 	 * Test if `wp_version_check` is blocked.
 	 *
-	 * It's possible to block updates with the `wp_version_check` filter, but this can't be checked during an
-	 * AJAX call, as the filter is never introduced then.
+	 * It's possible to block updates with the `wp_version_check` filter, but this can't be checked
+	 * during an Ajax call, as the filter is never introduced then.
 	 *
-	 * This filter overrides a normal page request if it's made by an admin through the AJAX call with the
-	 * right query argument to check for this.
+	 * This filter overrides a normal page request if it's made by an admin through the Ajax call
+	 * with the right query argument to check for this.
 	 *
 	 * @since 5.2.0
 	 */
@@ -233,8 +233,8 @@ class WP_Site_Health {
 	/**
 	 * Tests for WordPress version and outputs it.
 	 *
-	 * Gives various results depending on what kind of updates are available, if any, to encourage the
-	 * user to install security updates as a priority.
+	 * Gives various results depending on what kind of updates are available, if any, to encourage
+	 * the user to install security updates as a priority.
 	 *
 	 * @since 5.2.0
 	 *
@@ -334,7 +334,8 @@ class WP_Site_Health {
 	/**
 	 * Test if plugins are outdated, or unnecessary.
 	 *
-	 * The tests checks if your plugins are up to date, and encourages you to remove any that are not in use.
+	 * The tests checks if your plugins are up to date, and encourages you to remove any
+	 * that are not in use.
 	 *
 	 * @since 5.2.0
 	 *
@@ -465,8 +466,9 @@ class WP_Site_Health {
 	/**
 	 * Test if themes are outdated, or unnecessary.
 	 *
-	 * The tests checks if your site has a default theme (to fall back on if there is a need), if your themes
-	 * are up to date and, finally, encourages you to remove any themes that are not needed.
+	 * Сhecks if your site has a default theme (to fall back on if there is a need),
+	 * if your themes are up to date and, finally, encourages you to remove any themes
+	 * that are not needed.
 	 *
 	 * @since 5.2.0
 	 *
@@ -1408,11 +1410,11 @@ class WP_Site_Health {
 	/**
 	 * Test if debug information is enabled.
 	 *
-	 * When WP_DEBUG is enabled, errors and information may be disclosed to site visitors, or it may be
-	 * logged to a publicly accessible file.
+	 * When WP_DEBUG is enabled, errors and information may be disclosed to site visitors,
+	 * or logged to a publicly accessible file.
 	 *
-	 * Debugging is also frequently left enabled after looking for errors on a site, as site owners do
-	 * not understand the implications of this.
+	 * Debugging is also frequently left enabled after looking for errors on a site,
+	 * as site owners do not understand the implications of this.
 	 *
 	 * @since 5.2.0
 	 *
@@ -1589,8 +1591,8 @@ class WP_Site_Health {
 	/**
 	 * Test if scheduled events run as intended.
 	 *
-	 * If scheduled events are not running, this may indicate something with WP_Cron is not working as intended,
-	 * or that there are orphaned events hanging around from older code.
+	 * If scheduled events are not running, this may indicate something with WP_Cron is not working
+	 * as intended, or that there are orphaned events hanging around from older code.
 	 *
 	 * @since 5.2.0
 	 *
@@ -1661,8 +1663,9 @@ class WP_Site_Health {
 	/**
 	 * Test if WordPress can run automated background updates.
 	 *
-	 * Background updates in WordPress are primarily used for minor releases and security updates. It's important
-	 * to either have these working, or be aware that they are intentionally disabled for whatever reason.
+	 * Background updates in WordPress are primarily used for minor releases and security updates.
+	 * It's important to either have these working, or be aware that they are intentionally disabled
+	 * for whatever reason.
 	 *
 	 * @since 5.2.0
 	 *
@@ -1734,8 +1737,9 @@ class WP_Site_Health {
 	/**
 	 * Test if loopbacks work as expected.
 	 *
-	 * A loopback is when WordPress queries itself, for example to start a new WP_Cron instance, or when editing a
-	 * plugin or theme. This has shown itself to be a recurring issue as code can very easily break this interaction.
+	 * A loopback is when WordPress queries itself, for example to start a new WP_Cron instance,
+	 * or when editing a plugin or theme. This has shown itself to be a recurring issue,
+	 * as code can very easily break this interaction.
 	 *
 	 * @since 5.2.0
 	 *
@@ -2063,7 +2067,7 @@ class WP_Site_Health {
 		 *
 		 * @param array $test_type {
 		 *     An associative array, where the `$test_type` is either `direct` or
-		 *     `async`, to declare if the test should run via AJAX calls after page load.
+		 *     `async`, to declare if the test should run via Ajax calls after page load.
 		 *
 		 *     @type array $identifier {
 		 *         `$identifier` should be a unique identifier for the test that should run.
@@ -2071,7 +2075,7 @@ class WP_Site_Health {
 		 *         to avoid any collisions between tests.
 		 *
 		 *         @type string $label A friendly label for your test to identify it by.
-		 *         @type mixed  $test  A callable to perform a direct test, or a string AJAX action to be called
+		 *         @type mixed  $test  A callable to perform a direct test, or a string Ajax action to be called
 		 *                             to perform an async test.
 		 *     }
 		 * }
@@ -2148,8 +2152,9 @@ class WP_Site_Health {
 	/**
 	 * Check if any scheduled tasks have been missed.
 	 *
-	 * Returns a boolean value of `true` if a scheduled task has been missed and ends processing. If the list of
-	 * crons is an instance of WP_Error, return the instance instead of a boolean value.
+	 * Returns a boolean value of `true` if a scheduled task has been missed and ends processing.
+	 *
+	 * If the list of crons is an instance of WP_Error, return the instance instead of a boolean value.
 	 *
 	 * @since 5.2.0
 	 *
@@ -2173,8 +2178,9 @@ class WP_Site_Health {
 	/**
 	 * Check if any scheduled tasks are late.
 	 *
-	 * Returns a boolean value of `true` if a scheduled task is late and ends processing. If the list of
-	 * crons is an instance of WP_Error, return the instance instead of a boolean value.
+	 * Returns a boolean value of `true` if a scheduled task is late and ends processing.
+	 *
+	 * If the list of crons is an instance of WP_Error, return the instance instead of a boolean value.
 	 *
 	 * @since 5.3.0
 	 *
diff --git a/wp-admin/includes/template.php b/wp-admin/includes/template.php
index 1017e41417..3629a5ed3a 100644
--- a/wp-admin/includes/template.php
+++ b/wp-admin/includes/template.php
@@ -536,7 +536,7 @@ function wp_comment_trashnotice() {
 <div class="hidden" id="trash-undo-holder">
 	<div class="trash-undo-inside">
 		<?php
-		/* translators: %s: Comment author, filled by AJAX. */
+		/* translators: %s: Comment author, filled by Ajax. */
 		printf( __( 'Comment by %s moved to the Trash.' ), '<strong></strong>' );
 		?>
 		<span class="undo untrash"><a href="#"><?php _e( 'Undo' ); ?></a></span>
@@ -545,7 +545,7 @@ function wp_comment_trashnotice() {
 <div class="hidden" id="spam-undo-holder">
 	<div class="spam-undo-inside">
 		<?php
-		/* translators: %s: Comment author, filled by AJAX. */
+		/* translators: %s: Comment author, filled by Ajax. */
 		printf( __( 'Comment by %s marked as spam.' ), '<strong></strong>' );
 		?>
 		<span class="undo unspam"><a href="#"><?php _e( 'Undo' ); ?></a></span>
diff --git a/wp-admin/js/custom-background.js b/wp-admin/js/custom-background.js
index 346ae9c627..a08fb96c47 100644
--- a/wp-admin/js/custom-background.js
+++ b/wp-admin/js/custom-background.js
@@ -127,7 +127,7 @@
 				// Grab the selected attachment.
 				var attachment = frame.state().get('selection').first();
 
-				// Run an AJAX request to set the background image.
+				// Run an Ajax request to set the background image.
 				$.post( ajaxurl, {
 					action: 'set-background-image',
 					attachment_id: attachment.id,
diff --git a/wp-admin/js/customize-controls.js b/wp-admin/js/customize-controls.js
index 8b8c1fd67e..47272c8b3e 100644
--- a/wp-admin/js/customize-controls.js
+++ b/wp-admin/js/customize-controls.js
@@ -4440,7 +4440,7 @@
 
 		/**
 		 * Callback handler for when an attachment is selected in the media modal.
-		 * Does an additional AJAX request for setting the background context.
+		 * Does an additional Ajax request for setting the background context.
 		 */
 		select: function() {
 			api.UploadControl.prototype.select.apply( this, arguments );
diff --git a/wp-admin/js/dashboard.js b/wp-admin/js/dashboard.js
index bcdc783e70..581746bb45 100644
--- a/wp-admin/js/dashboard.js
+++ b/wp-admin/js/dashboard.js
@@ -64,7 +64,7 @@ jQuery(document).ready( function($) {
 	window.ajaxWidgets = ['dashboard_primary'];
 
 	/**
-	 * Triggers widget updates via AJAX.
+	 * Triggers widget updates via Ajax.
 	 *
 	 * @since 2.7.0
 	 *
@@ -103,7 +103,7 @@ jQuery(document).ready( function($) {
 		// If we have received a specific element to fetch, check if it is valid.
 		if ( el ) {
 			el = el.toString();
-			// If the element is available as AJAX widget, show it.
+			// If the element is available as Ajax widget, show it.
 			if ( $.inArray(el, ajaxWidgets) !== -1 ) {
 				// Show element without any delay.
 				show(0, el);
diff --git a/wp-admin/js/inline-edit-post.js b/wp-admin/js/inline-edit-post.js
index ac69f5c951..642bc4487b 100644
--- a/wp-admin/js/inline-edit-post.js
+++ b/wp-admin/js/inline-edit-post.js
@@ -385,7 +385,7 @@ window.wp = window.wp || {};
 
 	/**
 	 * Saves the changes made in the quick edit window to the post.
-	 * AJAX saving is only for Quick Edit and not for bulk edit.
+	 * Ajax saving is only for Quick Edit and not for bulk edit.
 	 *
 	 * @since 2.7.0
 	 *
diff --git a/wp-admin/js/media-gallery.js b/wp-admin/js/media-gallery.js
index 805a6f9260..7fe77a64ee 100644
--- a/wp-admin/js/media-gallery.js
+++ b/wp-admin/js/media-gallery.js
@@ -23,7 +23,7 @@ jQuery(function($) {
 			img_size = $( 'input[name="attachments[' + id + '][image-size]"]:checked').val();
 
 			/**
-			 * This AJAX action has been deprecated since 3.5.0, see custom-background.php
+			 * This Ajax action has been deprecated since 3.5.0, see custom-background.php
 			 */
 			jQuery.post(ajaxurl, {
 				action: 'set-background-image',
diff --git a/wp-admin/js/nav-menu.js b/wp-admin/js/nav-menu.js
index dd12c4f443..9f404f31a0 100644
--- a/wp-admin/js/nav-menu.js
+++ b/wp-admin/js/nav-menu.js
@@ -920,7 +920,7 @@
 				q = input.val();
 
 			/*
-			 * Minimum characters for a search. Also avoid a new AJAX search when
+			 * Minimum characters for a search. Also avoid a new Ajax search when
 			 * the pressed key (e.g. arrows) doesn't change the searched term.
 			 */
 			if ( q.length < minSearchLength || api.lastSearch == q ) {
diff --git a/wp-admin/js/plugin-install.js b/wp-admin/js/plugin-install.js
index f9c2be395d..8f417e5472 100644
--- a/wp-admin/js/plugin-install.js
+++ b/wp-admin/js/plugin-install.js
@@ -150,7 +150,7 @@ jQuery( document ).ready( function( $ ) {
 
 	/*
 	 * Open the Plugin details modal. The event is delegated to get also the links
-	 * in the plugins search tab, after the AJAX search rebuilds the HTML. It's
+	 * in the plugins search tab, after the Ajax search rebuilds the HTML. It's
 	 * delegated on the closest ancestor and not on the body to avoid conflicts
 	 * with other handlers, see Trac ticket #43082.
 	 */
diff --git a/wp-admin/js/post.js b/wp-admin/js/post.js
index cc7cab1a72..f6da847f9c 100644
--- a/wp-admin/js/post.js
+++ b/wp-admin/js/post.js
@@ -29,7 +29,7 @@ window.wp = window.wp || {};
 		st : 0,
 
 		/**
-		 * Fetch comments using AJAX and display them in the box.
+		 * Fetch comments using Ajax and display them in the box.
 		 *
 		 * @memberof commentsBox
 		 *
@@ -938,7 +938,7 @@ jQuery(document).ready( function($) {
 
 	/**
 	 * Handle the editing of the post_name. Create the required HTML elements and
-	 * update the changes via AJAX.
+	 * update the changes via Ajax.
 	 *
 	 * @global
 	 *
diff --git a/wp-admin/js/tags-box.js b/wp-admin/js/tags-box.js
index 40105e2d38..7d7eee53f1 100644
--- a/wp-admin/js/tags-box.js
+++ b/wp-admin/js/tags-box.js
@@ -284,8 +284,8 @@
 			 *
 			 * @since 2.9.0
 			 *
-			 * @param {number|string} r The response message from the AJAX call.
-			 * @param {string} stat The status of the AJAX request.
+			 * @param {number|string} r The response message from the Ajax call.
+			 * @param {string} stat The status of the Ajax request.
 			 *
 			 * @return {void}
 			 */
diff --git a/wp-admin/js/updates.js b/wp-admin/js/updates.js
index 761f31fdd2..dc342f281d 100644
--- a/wp-admin/js/updates.js
+++ b/wp-admin/js/updates.js
@@ -11,7 +11,7 @@
  * @param {jQuery}  $                                   jQuery object.
  * @param {object}  wp                                  WP object.
  * @param {object}  settings                            WP Updates settings.
- * @param {string}  settings.ajax_nonce                 AJAX nonce.
+ * @param {string}  settings.ajax_nonce                 Ajax nonce.
  * @param {object=} settings.plugins                    Base names of plugins in their different states.
  * @param {Array}   settings.plugins.all                Base names of all plugins.
  * @param {Array}   settings.plugins.active             Base names of active plugins.
@@ -1531,9 +1531,9 @@
 	 * @since 4.6.0
 	 * @private
 	 *
-	 * @param {object} data   AJAX payload.
+	 * @param {object} data   Ajax payload.
 	 * @param {string} action The type of request to perform.
-	 * @return {object} The AJAX payload with the appropriate callbacks.
+	 * @return {object} The Ajax payload with the appropriate callbacks.
 	 */
 	wp.updates._addCallbacks = function( data, action ) {
 		if ( 'import' === pagenow && 'install-plugin' === action ) {
@@ -1769,7 +1769,7 @@
 	};
 
 	/**
-	 * Validates an AJAX response to ensure it's a proper object.
+	 * Validates an Ajax response to ensure it's a proper object.
 	 *
 	 * If the response deems to be invalid, an admin notice is being displayed.
 	 *
diff --git a/wp-includes/functions.php b/wp-includes/functions.php
index 91d111e9e2..b71512b803 100644
--- a/wp-includes/functions.php
+++ b/wp-includes/functions.php
@@ -3575,7 +3575,7 @@ function _default_wp_die_handler( $message, $title = '', $args = array() ) {
  * @param string|array $args    Optional. Arguments to control behavior. Default empty array.
  */
 function _ajax_wp_die_handler( $message, $title = '', $args = array() ) {
-	// Set default 'response' to 200 for AJAX requests.
+	// Set default 'response' to 200 for Ajax requests.
 	$args = wp_parse_args(
 		$args,
 		array( 'response' => 200 )
diff --git a/wp-includes/js/customize-models.js b/wp-includes/js/customize-models.js
index 0a8bca7f47..e72266327a 100644
--- a/wp-includes/js/customize-models.js
+++ b/wp-includes/js/customize-models.js
@@ -13,7 +13,7 @@
 	 * wp.customize.HeaderTool.ImageModel
 	 *
 	 * A header image. This is where saves via the Customizer API are
-	 * abstracted away, plus our own AJAX calls to add images to and remove
+	 * abstracted away, plus our own Ajax calls to add images to and remove
 	 * images from the user's recently uploaded images setting on the server.
 	 * These calls are made regardless of whether the user actually saves new
 	 * Customizer settings.
diff --git a/wp-includes/js/heartbeat.js b/wp-includes/js/heartbeat.js
index f55d2f87ca..aff58b12a3 100644
--- a/wp-includes/js/heartbeat.js
+++ b/wp-includes/js/heartbeat.js
@@ -68,7 +68,7 @@
 				// Used when the interval is reset.
 				originalInterval: 0,
 
-				// Used to limit the number of AJAX requests.
+				// Used to limit the number of Ajax requests.
 				minimalInterval: 0,
 
 				// Used together with tempInterval.
@@ -146,7 +146,7 @@
 				}
 
 				/*
-				 * Used to limit the number of AJAX requests. Overrides all other intervals
+				 * Used to limit the number of Ajax requests. Overrides all other intervals
 				 * if they are shorter. Needed for some hosts that cannot handle frequent requests
 				 * and the user may exceed the allocated server CPU time, etc. The minimal interval
 				 * can be up to 600 seconds, however setting it to longer than 120 seconds
diff --git a/wp-includes/js/media-models.js b/wp-includes/js/media-models.js
index 96947b2e72..4bb86c25fd 100644
--- a/wp-includes/js/media-models.js
+++ b/wp-includes/js/media-models.js
@@ -882,7 +882,7 @@ var Attachments = Backbone.Collection.extend(/** @lends wp.media.model.Attachmen
 		return this.mirroring ? this.mirroring.hasMore() : false;
 	},
 	/**
-	 * A custom AJAX-response parser.
+	 * A custom Ajax-response parser.
 	 *
 	 * See trac ticket #24753
 	 *
diff --git a/wp-includes/js/plupload/handlers.js b/wp-includes/js/plupload/handlers.js
index 9ed2cc687d..1edfc5cf42 100644
--- a/wp-includes/js/plupload/handlers.js
+++ b/wp-includes/js/plupload/handlers.js
@@ -148,7 +148,7 @@ function prepareMediaItemInit( fileObj ) {
 	// Replace the original filename with the new (unique) one assigned during upload.
 	jQuery( '.filename.original', item ).replaceWith( jQuery( '.filename.new', item ) );
 
-	// Bind AJAX to the new Delete button.
+	// Bind Ajax to the new Delete button.
 	jQuery( 'a.delete', item ).click( function(){
 		// Tell the server to delete it. TODO: Handle exceptions.
 		jQuery.ajax({
@@ -166,7 +166,7 @@ function prepareMediaItemInit( fileObj ) {
 		return false;
 	});
 
-	// Bind AJAX to the new Undo button.
+	// Bind Ajax to the new Undo button.
 	jQuery( 'a.undo', item ).click( function(){
 		// Tell the server to untrash it. TODO: Handle exceptions.
 		jQuery.ajax({
diff --git a/wp-includes/js/wp-lists.js b/wp-includes/js/wp-lists.js
index d53ab6c51e..d24f2c1efd 100644
--- a/wp-includes/js/wp-lists.js
+++ b/wp-includes/js/wp-lists.js
@@ -294,7 +294,7 @@ wpList = {
 	},
 
 	/**
-	 * Adds an item to the list via AJAX.
+	 * Adds an item to the list via Ajax.
 	 *
 	 * @param {HTMLElement} element  The DOM element.
 	 * @param {object}      settings Settings for this list.
@@ -396,7 +396,7 @@ wpList = {
 	},
 
 	/**
-	 * Delete an item in the list via AJAX.
+	 * Delete an item in the list via Ajax.
 	 *
 	 * @param {HTMLElement} element  A DOM element containing item data.
 	 * @param {object}      settings Settings for this list.
@@ -483,7 +483,7 @@ wpList = {
 	},
 
 	/**
-	 * Dim an item in the list via AJAX.
+	 * Dim an item in the list via Ajax.
 	 *
 	 * @param {HTMLElement} element  A DOM element containing item data.
 	 * @param {object}      settings Settings for this list.
diff --git a/wp-includes/load.php b/wp-includes/load.php
index 981bf8474e..74f48c1f90 100644
--- a/wp-includes/load.php
+++ b/wp-includes/load.php
@@ -891,7 +891,7 @@ function is_protected_endpoint() {
 		return true;
 	}
 
-	// Protect AJAX actions that could help resolve a fatal error should be available.
+	// Protect Ajax actions that could help resolve a fatal error should be available.
 	if ( is_protected_ajax_action() ) {
 		return true;
 	}
@@ -901,21 +901,22 @@ function is_protected_endpoint() {
 	 *
 	 * This filter is only fired when an endpoint is requested which is not already protected by
 	 * WordPress core. As such, it exclusively allows providing further protected endpoints in
-	 * addition to the admin backend, login pages and protected AJAX actions.
+	 * addition to the admin backend, login pages and protected Ajax actions.
 	 *
 	 * @since 5.2.0
 	 *
-	 * @param bool $is_protected_endpoint Whether the currently requested endpoint is protected. Default false.
+	 * @param bool $is_protected_endpoint Whether the currently requested endpoint is protected.
+	 *                                    Default false.
 	 */
 	return (bool) apply_filters( 'is_protected_endpoint', false );
 }
 
 /**
- * Determines whether we are currently handling an AJAX action that should be protected against WSODs.
+ * Determines whether we are currently handling an Ajax action that should be protected against WSODs.
  *
  * @since 5.2.0
  *
- * @return bool True if the current AJAX action should be protected.
+ * @return bool True if the current Ajax action should be protected.
  */
 function is_protected_ajax_action() {
 	if ( ! wp_doing_ajax() ) {
@@ -938,13 +939,13 @@ function is_protected_ajax_action() {
 	);
 
 	/**
-	 * Filters the array of protected AJAX actions.
+	 * Filters the array of protected Ajax actions.
 	 *
-	 * This filter is only fired when doing AJAX and the AJAX request has an 'action' property.
+	 * This filter is only fired when doing Ajax and the Ajax request has an 'action' property.
 	 *
 	 * @since 5.2.0
 	 *
-	 * @param string[] $actions_to_protect Array of strings with AJAX actions to protect.
+	 * @param string[] $actions_to_protect Array of strings with Ajax actions to protect.
 	 */
 	$actions_to_protect = (array) apply_filters( 'wp_protected_ajax_actions', $actions_to_protect );
 
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 3d1e718062..73847cf174 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.5-alpha-48167';
+$wp_version = '5.5-alpha-48168';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.