New Pipe Smoker With A Question? Ask an Old Fart

[alley00p]

I'd like to ask a newbie question. What do many of you mean when you talk about rubbing out some tabak before filling your pipe bowl?

There are some terms used by many of you that just don't compute to this newbie smoker.

I've always just filled the bowl with the chosen tobacco, lit, it and commenced smoking.
What am I missing here?

Thanks in advance!