Which statement best defines an algorithm?

An algorithm is defined as a step-by-step procedure for solving a problem. This definition captures the essence of what an algorithm is: a clearly defined series of instructions or processes that lead to the solution of a specific problem or task. It emphasizes the systematic approach involved in problem-solving, which is fundamental to both programming and mathematical computations.

In the context of algorithms, each step must be precise and unambiguous, allowing it to be followed in order to achieve the desired outcome. This structured approach is crucial because it helps in breaking down complex problems into manageable parts, allowing for effective analysis and solution.

The other options do not accurately characterize an algorithm. A process designed to run indefinitely does not correlate to the concept of an algorithm, as algorithms are intended to provide a finite answer or solution. A collection of functions for data manipulation relates more to programming libraries or frameworks rather than the concept of an algorithm itself. Similarly, a type of user interface is entirely outside the realm of what an algorithm represents, as algorithms do not involve the interaction between the user and a system in that way.