Gaming online?

I'm new to online gaming but when it says it's 'free' to go online with your PS3... what does that exactly mean? Obviously downloading games etc. you need to pay, but I've been playing Wipeout HDand WKC online and not sure if that takes your monthly limit from my ISP.

Playing the games online doesn't cost like XBL does but you will still use up your data cap. Don't worry, it's only about 30MB per hour though.gamebreakerz__

Edit: Nevermind, stupid question.