A loop inside another loop is called?

A loop inside another loop is referred to as a nested loop. This structure allows for multiple iterations over a set of items, which is particularly useful when dealing with multi-dimensional data structures, such as arrays or matrices. For instance, in a nested loop, the outer loop may iterate over rows while the inner loop iterates over columns, enabling you to access each element in the matrix systematically.

Nested loops facilitate complex operations, as you can execute one loop's iterations completely for every instance of the outer loop. This is critical in scenarios such as matrix multiplication, where each element of a row needs to be multiplied by each element of a column.

Understanding nested loops is essential for solving problems that involve repeated execution of code blocks where the number of iterations is determined by the conditions of both the outer and inner loops. This concept is foundational in programming and helps in managing more intricate iterations within data structures.