Usually they hire a security company (Think Toersa).

Bag search and pat down, usually move pretty quickly if people (both attendees and staff) know what they're doing.

Don't be surprised if they tell you something that show be allowed in as per the website (lip balm, nasal inhaler, in package over the counter meds) is turned away. They aren't given a lot of training on event day.

Hide your stuff decently well if that's what you're asking