Tech talks / meet ups, what to expect?

So, I have been invited by a job agency to like a tech talk or a meetup in my local area. I’m undecided if I should go, the idea of it makes me feel a bit nervous.

I was wondering if any of you have been to one of these meetups (obviously not the same one), and what should I expect? Was there a lot of crowd participation, or was it just like a presentation thing? Did you enjoy it?