What does block diagram decomposition mean?

Question

block diagram

Hello! Please help me understand what is block diagram decomposition? I tried to search for a solution on the Internet, but it was not possible to find material that would be clear to me in full.
At its core, decomposition is the division of a whole into parts, but what should a decomposition algorithm look like? If possible, please provide a simplified example.

Answer 1

If possible, please provide a simplified example.

Without decomposition: click on the link
With decomposition: take the mouse in hand - move the cursor over the link - click LMB - release LMB

Answer 2

Typically, decomposition refers to the subject area. When objects from a task (subject area) are transferred to flowcharts, uml diagrams and the like.