Terraform variable type constraints specify allowed data types for input variables. They include primitive types (string, number, bool), complex types (list, set, map, object), and any for unspecified types. Constraints can enforce specific structures, nested types, or value ranges. They’re defined in the variable block’s type argument, helping catch errors early and ensuring correct variable usage throughout configurations.

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                                                                          - [officialVariable Type Constraints](https://developer.hashicorp.com/terraform/language/expressions/type-constraints)
                                                                          - [videoTerraform Type Constraints](https://www.youtube.com/watch?v=hNZiZEQfV4Q)