This article discusses the usage of built-in functions in Terraform, specifically the `try`, `can`, and `lookup` functions. The `try` function evaluates all its argument expressions in turn and returns the result of the first one that does not produce any errors. It is used for concise testing of the presence of and types of object attributes. The `can` function evaluates an expression and returns a boolean value indicating whether it succeeded. The `lookup` function retrieves the value of a map element or list element. These functions are compared, with `try` being a more general form of `lookup`. Additionally, the article provides examples of how to use these functions in various scenarios.