This may seem like a total noob question but I just don't get it. You mean to tell me that companies pay a $.10 - $1 to have 1 click to their site? Does the person have to stay on their site for a certain amount of time?
That's correct. You get paid for every valid click and there are no time limits for getting paid for the click.
The three main types of ads are: CPM - You get paid regardless if the visitor does anything... no click required. CPC - You get paid if they click on it... doesn't matter what else they do or if they immediately close the window that opens, you still get paid. CPA - You get paid if they click on the ad, go to the advertiser's site, and then do something else on that site. It could be anything... sign up for newsletter, buy something, look at something, read something. Generally the payout goes up by a lot as you move from CPM to CPC to CPA. You might get $1 for 1,000 users with CPM, where with CPC you might get $1 if 1 user clicks. However, with CPA, you might get $10 if 1 user does something on the site.