| --- |
| page_title: Functions - Configuration Language |
| 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](/terraform/tutorials/configuration-language/functions?utm_source=WEBSITE&utm_medium=WEB_IO&utm_offer=ARTICLE_PAGE&utm_content=DOCS) tutorial. |
| |
| 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_](/terraform/language/expressions/function-calls) |
| 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 documentation includes a page for 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](/terraform/cli/commands/console): |
| |
| ``` |
| > 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. |
