Do you have to pre-register for panels at Comic-Con?

[flipmunkee]

I haven't been to SDCC in about 10 years and back then I only went to the convention floor. This year I'm interested in visiting some of the panels and stuff but I was just wondering if you have to pre-register for them? Or do you just line up and it's first come first served?

For example, say I wanted to attend the panel on 'Lost' (just an example). Would I just show up to the room at the time it starts?

Thanks for any help!