Until now i have always used the 'two space' rule after a period. The only reason i can put my 'two space passion' down to was seeing my mother typing when i was a kid and asking her why she put two spaces after the period. It was, as Bill points out in this video, was because in a fixed width font system you needed more space after the period to make it readable. Funny thing is ... that i have just realised that as i am typing this i am still putting two spaces in :) It is a natural thing for me now... but something i will change after watching this video. Bill is funny to listen to.