What is a loop in programming?

A loop in programming refers to a control structure that allows a sequence of instructions to be executed repeatedly until a specified condition is met. This mechanism is fundamental in programming because it enables the execution of a block of code multiple times without needing to duplicate that code.

For example, loops are often used for iterating over collections, performing repeated calculations, or managing tasks that need to be executed numerous times, such as processing items in a list. In a typical loop structure, such as a 'for' or 'while' loop, a condition is checked before each iteration; if the condition evaluates to true, the loop executes the code block, and the process continues until the condition becomes false. This repetition makes loops highly efficient for automating repetitive tasks in a program.

Understanding loops is essential for mastering control flow in programming, which fundamentally governs how a program executes its instructions based on certain conditions.