File Shrinkage

Sorry, there is probably a perfectly good explaination for this, but I’d be grateful if anyone could explain it to me.

I’m writing a rather large document and have been working on it for a few weeks now. I save everytime I close it and regularly throughtout the writing process.

I sent a copy of it as I had it a few days ago to a friend and it went at 91kb. I’ve since added another 20 pages (in Word) and sent it again. This time it went at 86kb. I can’t understand how it’s gotten smaller. Looked at the last page, but it seems to be all there and haven’t got time to read it all through today to see if anything is missing.

Does word have a file compression system? I’m on XP and I’m not very computer literate, so monosylabic words only please!