When would you typically use a nested loop?

A nested loop is typically used when you need to perform iterative tasks that involve multidimensional data structures, such as grids or matrices. This is because a nested loop allows you to iterate through each element of a structure that contains multiple levels of data, effectively allowing you to access and manipulate each element in a more complex data arrangement.

For example, if you are generating a two-dimensional grid, you would use an outer loop to iterate through rows and an inner loop to iterate through the columns within those rows. This structure enables you to fill in, display, or compute values for each individual cell in the grid format.

In contrast, when repeating a single instruction, a simple loop is sufficient and efficient, as nesting is unnecessary. Likewise, interacting with user input typically involves conditionals and single loops to gather and process data sequentially rather than in a multidimensional context. Defining classes relates to object-oriented programming and typically does not involve iterative processes, thus not requiring nested loops.