[[servlet-authentication-unpwd]]
= Username/Password Authentication
:figures: images/servlet/authentication/unpwd
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One of the most common ways to authenticate a user is by validating a username and password.
As such, Spring Security provides comprehensive support for authenticating with a username and password.

[[servlet-authentication-unpwd-input]]
== Reading the Username & Password

Spring Security provides the following built in mechanisms for reading a username and password from the `HttpServletRequest`:

* xref:servlet/authentication/passwords/form.adoc#servlet-authentication-form[Form Login]
* xref:servlet/authentication/passwords/basic.adoc#servlet-authentication-basic[Basic Authentication]
* xref:servlet/authentication/passwords/digest.adoc#servlet-authentication-digest[Digest Authentication]

[[servlet-authentication-unpwd-storage]]
== Storage Mechanisms

Each of the supported mechanisms for reading a username and password can leverage any of the supported storage mechanisms:

* Simple Storage with xref:servlet/authentication/passwords/in-memory.adoc#servlet-authentication-inmemory[In-Memory Authentication]
* Relational Databases with xref:servlet/authentication/passwords/jdbc.adoc#servlet-authentication-jdbc[JDBC Authentication]
* Custom data stores with xref:servlet/authentication/passwords/user-details-service.adoc#servlet-authentication-userdetailsservice[UserDetailsService]
* LDAP storage with xref:servlet/authentication/passwords/ldap.adoc#servlet-authentication-ldap[LDAP Authentication]