What is a programming term for a small region of reusable source code?

A small region of reusable source code is referred to as a code snippet. This term is commonly used in programming to describe a piece of code that can be easily inserted or reused in different parts of a program or across projects. Code snippets are particularly valuable for tasks that require repeated implementation of similar functionalities, making coding more efficient and reducing the potential for errors due to repetition.

In contrast, a code segment generally refers to a larger block of code that may not necessarily be intended for reuse, while a function is a specific construct that performs a particular task and is defined with parameters and a return value. A variable, on the other hand, is a named storage location in programming that holds data, as opposed to being a compact block of code itself. Thus, the term "code snippet" accurately encapsulates the concept of a small, reusable segment of code.