# Expressions

Aqua file consists of a header and a body.

###

### Body expressions

`func`

Function definition is the most crucial part of the language, see [Functions](functions.md) for details.

``

{% embed url="https://github.com/fluencelabs/aqua/tree/main/semantics/src/main/scala/aqua/semantics/expr" %}
Expressions source code
{% endembed %}
