It's a little different for every tournament that is played, but you can find examples at the pages hosting the tournaments... Here's one for the MGC:

http://www.midwestgamingclassic.com/tournaments/pinball-tournaments/mpc-rules/

I don't like the term "Herb format", I like it as "open qualifying." It isn't just something to send the prize pools through the roof - it actually helps not-so-great players have a chance too. If you are inconsistent, and you play a game and you just stink, in "open qualifying" you can play it again to try to improve your score. If you are playing in PAPA style, head to head, or limited entry, it very hard to bounce back from a lower score.

Re: herbertsharpe - Hey, no...

Using me as an example, I'm generally a pretty decent pinball player. Using my friends as an example, if we play 20 games, I'll win probably 16 of them. Good percentage. On three of those games, it will probably be pretty close, and the other player will have had a good game. On one of those games, I will score like 1/30th of their score.

Open qualifying format helps me as a player because if in qualifying, I get that 1/30th of a score, I can play again and wipe it out. I'm not though good enough to not have games that just suck sometimes.

So for me, this is a much better way to play. I get a chance to play and with a few scores, I get to see where I stand. If I bomb the same game but am okay on the other 4 or whatever, I can opt to replay it.

Also, contrary to what some people have said, I don't get what people mean by you have to "grind" it out. If you set a monster score on a game as your first play, chances are you don't need to play it again. Generally, the top qualifying people won't be playing all day, unless they want to get a continued "feel" for the machines and / or try to hold their spots. We have had some people qualifying in the first two hours Saturday and then not play another entry.

I don't like to "loose" money either...

It depends. In our tournament format, we give out stuff to something like the top 44 players. Based on our qualifying pool in most years, that means nearly 50% get to play for something, and competing in a setting where there is something on the line is fun. Besides that, there is a chance that someone can play better than expected. A couple years ago, a guy who never played in a tournament until our show took part and got third, while playing against people who were top 25 players in the world. The following year I think it was, we had a player win who it was his third tournament.

I think it's worth playing in at least one to see what you think of it

Well... good! I only care that people have fun, really.

A few years ago, my mom played in the tournament. She won't even play my games, I offered to buy her a couple entries for he staying so late, and much to my surprise she said sure.

After that, I would get regular updates about what rank she was in the world. There truly is something fun that just about anyone can find in a tournament