One of the principal dimensions for the understanding of any programming language is its type system: what are the types of values allowed in the language and how can they be manipulated.

Although machine assembly language and some other languages such as BCPL are untyped, organizing the value spaces of a programming language into types is generally very helpful for organizing the programs.

• Strong and Weak Typing

• Type Conversions

• Mathematical Models of Structured Data Types

• Parameterized Types: Parametric Polymorphism

• Issues in Type Systems

• Type Conversion

• Subtype Polymorphism: Object-Oriented Subclassing