# What are functions

Functions in AIsuru let your Agent extend its capabilities beyond simple conversation. There are two main types of functions:

1. Built-in functions ("AIsuru Functions"):
   1. Pre-configured tools that are ready to use;
   2. Include features like sending emails and searching the web;
   3. Easy to enable and use without complex configuration.
2. Custom functions ("Advanced functions"):
   1. Let you create custom integrations with external services;
   2. Allow you to automate complex processes;
   3. Require more detailed technical configuration.

With functions you can:

* Retrieve information from external sources in real time;
* Automate repetitive actions;
* Customize the Agent's responses based on specific data;
* Integrate the Agent with other systems and services.

In the next sections we'll explore in detail:

* The [built-in functions](/en/advanced-features/integrations/functions/aisuru-functions.md) available in AIsuru;
* How to configure and use [advanced functions](/en/advanced-features/integrations/functions/advanced-functions.md) for specific use cases.


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