Which structure is typically used for repeating actions in Karel's programming?

In Karel's programming, loops are the fundamental structure used for repeating actions. Loops allow a set of instructions to be executed multiple times, which is essential for tasks that require repetitive behavior, such as moving forward a certain number of steps, picking up a specific number of beepers, or turning until a specific condition is met.

Loops can be implemented in different forms, such as 'while' loops or 'for' loops, which provide flexibility in controlling the repeated execution based on various conditions. By utilizing loops, programmers can create efficient and concise code that avoids redundancy and enhances readability. This is especially important in Karel's environment, where tasks often involve navigating a grid and performing similar actions on multiple iterations.

Other structures mentioned in the question serve different purposes. Conditions are used for decision-making, subroutines allow the creation of reusable code segments, and variables are used to store data values, but none of these directly facilitate repetition in the same way that loops do.