What does a substring do in programming?

A substring is a sequence of characters that is extracted from a larger string, and it specifically takes characters from a list or string between two specified indices. The process involves selecting a starting index and an ending index, allowing the programmer to isolate a portion of the original string for various purposes, such as manipulation, display, or analysis.

In programming, this functionality is vital as it enables developers to handle strings more effectively. By specifying the indices, a substring can be tailored to include exactly the characters needed, which can be crucial for tasks like parsing data or handling user input. Substrings are commonly used in many programming languages through built-in functions or methods, supporting tasks such as validating input, searching for patterns, or reformulating output.

This understanding of substrings is key to manipulating text in applications, making them a foundational concept in software and app design.