Blocks: draw once, use forever

Module 3 ended with a promise: the TOILET, BASIN and SHOWER stamps you carved for the apartment bathroom were a treasure chest waiting to be opened properly. Time to open it. This lesson turns blocks from a convenience into a system — the system that means you will never draw a toilet, a door or a window again for the rest of your career.

Definitions and inserts: one master, many copies

Here is what actually happened when you pressed B in Module 3. AutoCAD did not merely group some lines. It stored a block definition — a master copy of the toilet — in the drawing's internal library, then placed an insert pointing at it. Every INSERT after that placed another pointer. Ten toilets on screen is really ONE toilet, referenced ten times.