In flow diagrams, what is represented by a box containing other boxes?

A box containing other boxes in a flow diagram indicates a subroutine, which is a block of code or a set of instructions that perform a specific task within a larger program. This hierarchical structure helps organize complex processes by encapsulating repeated or related tasks, making the flowchart easier to read and manage.

In this context, a subroutine allows for modular programming, where specific functionalities can be reused without repeating code, improving efficiency and clarity. By highlighting the subroutine in a flow diagram, it signals to the viewer that the main flow of the program can call this block to perform its designated tasks. This feature is essential in programming and flowchart design to help clarify how different parts of a program interact and function together.