terraform/website/docs/language/functions/index.html.md

---
layout: "language"
page_title: "Functions - Configuration Language"
sidebar_current: "docs-config-functions"
description: "An introduction to the built-in functions that you can use to transform and combine values in expressions."
---

# Built-in Functions

> **Hands-on:** Try the [Perform Dynamic Operations with Functions](https://learn.hashicorp.com/tutorials/terraform/functions?in=terraform/configuration-language&utm_source=WEBSITE&utm_medium=WEB_IO&utm_offer=ARTICLE_PAGE&utm_content=DOCS) tutorial on HashiCorp Learn.

The Terraform language includes a number of built-in functions that you can
call from within expressions to transform and combine values. The general
syntax for function calls is a function name followed by comma-separated
arguments in parentheses:

```hcl
max(5, 12, 9)
```

For more details on syntax, see
[_Function Calls_](/docs/language/expressions/function-calls.html)
in the Expressions section.

The Terraform language does not support user-defined functions, and so only
the functions built in to the language are available for use. The navigation
for this section includes a list of all of the available built-in functions.

You can experiment with the behavior of Terraform's built-in functions from
the Terraform expression console, by running
[the `terraform console` command](/docs/cli/commands/console.html):

```
> max(5, 12, 9)
12
```

The examples in the documentation for each function use console output to
illustrate the result of calling the function with different parameters.