Programs are made up of (or constructed from) programming language constructs. A programming language construct is a portion of the program that defines an entity within it.

A programming language construct can be defined as any building block of the program. Each of the following can be viewed as a programming language construct:

• statement
• statement block
• keyword
• subroutine
• comment
• data item
• data type
• operator
• namespace
• class

In source code constructs are made up of characters which can be either digit or non-digit characters.