Backstage passes are basically a piece of laminated paper that can be worn either hanging around the neck or clipped on a belt. This serves as a business card of sorts, which announces the bearer's connection to the event. They are usually issued to employees, so fans with access to one can usually get into areas not open to the regular public. There are basically four types: all-access passes, stage crew passes, limited access passes, and "sticky passes."
All-access and stage crew passes are issued to employees only. This can refer to anybody working on the concert, from the performers themselves to the people who set-up the stage. Some workers may be issued temporary passes that have a definite date on them, which means that the workers are only granted access privileges during the time specified but should leave the premises by the time the concert starts. Depending on the event and the venue, these types of backstage passes may include certain security measures, such as holograms, raised writing, or a signature from the performers themselves.
Limited access passes are the most common type issued to fans. This type of pass allows people not connected to the event to go backstage and meet the performers, tour the facilities, and see the inner workings of the event. They are sometimes called VIP passes, and may or may not include access to dressing rooms and afterparties.
The "sticky pass" is one of the most sought-after types of backstage passes. They're given to friends, family, and other individuals connected to the band. They are also sometimes won in contests or given away by radio stations. This kind of pass provides access to afterparties and allows the bearer to mingle with crew members, performers, and VIP guests.
Backstage passes can sometimes become collector's items, especially if the band is no longer together or if the pass itself is signed by the performer.