# Step 5: Extensions

Exago comes with a high degree of extensibility. For a quick overview of some of the ways an administrator can configure Exago to have custom functionality, see the article below:

An Overview of Exago Extensions

Following are some of the methods by which custom behavior can be added to Exago:

# Formulas

Formulas are used in many aspects of report design and allow the user to perform calculations, call administrator-defined functions, and much more.

# Server Events

Server Events allow an administrator to plug in custom logic using C#, VB.NET, or JavaScript during report execution as well as several other places in the Exago flow.

# Action Events

Action Events give the administrator the ability to execute both client-side and server-side code in response to a UI event.

# Themes

Customized Themes are available for several different Exago features, including reports, charts, maps, and gauges.

# Custom Filter Functions

Custom Filter Functions give the ability to add to Exago's built-in filter function list which includes functions like `Today()` and `FirstDayOfLastYear().`

For more information on Exago extensibility, check out the Extensibility section of the Support Center.

Step 4: Administration Console and API