A struct is a composite_type that groups named fields with specific types into one record_type. Use dot_notation to access a field. Create one with initialization using field values or defaults. Many languages allow methods on a struct. Passing a struct may use value_semantics or references, depending on the language. A struct supports type_definition and reuse across code. It stores related data together for clearer, safer code. Remember: names, types, and order often affect its memory_layout.