What does a loop do in Python?

In Python, a loop serves the essential function of repeating a block of code multiple times until a specified condition is met. This capability allows developers to execute a set of instructions without manually writing them out for each iteration. For instance, using a for loop, you can iterate over a sequence (like a list or a string) and perform actions for each element in that sequence. Similarly, a while loop continues executing its block of code as long as a given condition evaluates to true. This mechanism is particularly useful for tasks such as iterating over collections, processing data, or executing repetitive actions without redundancy in code.

The other options provided do not accurately describe the role of a loop in Python. Stopping execution pertains to control statements or termination conditions, catching exceptions relates to error handling in programming, and defining new data types involves creating classes or data structures rather than the iterative process a loop provides. Thus, the ability of loops to repeat code is a fundamental concept that enhances code efficiency and maintainability.