The purpose of an algorithm in computer science is to provide a step-by-step procedure for solving a problem or performing a computation. Algorithms are fundamental to programming and software development, as they dictate how data is processed, sorted, and manipulated. They facilitate efficiency by determining the most effective methods to execute functions, such as searching or sorting large datasets. By clearly defining the logic required to solve specific tasks, algorithms enable programmers to build scalable and robust applications that can handle complex operations.