A type system is a set of rules that defines how different data types can be used in programming languages. It helps ensure that operations on data are performed correctly, preventing errors that can occur when incompatible types are mixed. Common data types include integers, strings, and booleans, each serving specific purposes in code. Type systems can be classified as either static or dynamic. In a static type system, types are checked at compile time, while in a dynamic type system, types are checked at runtime. This distinction affects how developers write and debug their code, influencing overall software reliability and performance.