[role="xpack"]
[testenv="basic"]
[[eql]]
= EQL for event-based search
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<titleabbrev>EQL</titleabbrev>
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experimental::[]

{eql-ref}/index.html[Event Query Language (EQL)] is a query language used for
logs and other event-based data.

You can use EQL in {es} to easily express relationships between events and
quickly match events with shared properties. You can use EQL and query
DSL together to better filter your searches.

[float]
[[eql-advantages]]
=== Advantages of EQL

* *EQL lets you express relationships between events.* +
Many query languages allow you to match only single events. EQL lets you match a
sequence of events across different event categories and time spans.

* *EQL has a low learning curve.* +
EQL syntax looks like other query languages. It lets you write and read queries
intuitively, which makes for quick, iterative searching.

* *We designed EQL for security use cases.* +
While you can use EQL for any event-based data, we created EQL for threat
hunting. EQL not only supports indicator of compromise (IOC) searching but
makes it easy to describe activity that goes beyond IOCs.

[float]
[[when-to-use-eql]]
=== When to use EQL

Consider using EQL if you:

* Use {es} for threat hunting or other security use cases
* Search time-series data or logs, such as network or system logs
* Want an easy way to explore relationships between events

[float]
[[eql-toc]]
=== In this section

* <<eql-requirements>>
* <<eql-search>>
* <<eql-syntax>>
* <<eql-function-ref>>
* <<eql-limitations>>

include::requirements.asciidoc[]
include::search.asciidoc[]
include::syntax.asciidoc[]
include::functions.asciidoc[]
include::limitations.asciidoc[]