Every concert you go to may be different, but you can always identify the people who are truly enjoying themselves versus the people who got dragged to the show. These are the five basic categories you can group concert-goers into no matter what type of concert you're going to.
1. Die hard fan
The most obvious category to identify. Depending on the concert, these people probably already own a t-shirt repping this band. They will most likely be screaming and cheering the loudest during the performance, and they will most definitely be interacting with the band. For example, when the band says "How are we doing tonight, insert city name here?" they will most definitely scream. And most definingly, they will definitely know all the words to the band's songs, even the most unpopular ones.
2. The obviously drunk person
This type of person actually shares many characteristics with the die hard fan. They will be incredibly loud, and they will also interact with the band. But the way in which these things are done is quite different. You can easily identify the drunk person at a concert because they will never sit/stand still, they react at inappropriate times, and frankly they just tend to draw a lot of attention to themselves.
3. Mainstream fans
These are the people that know a band by the songs played on the radio. They definitely don't know all of the songs by the band, but you can bet they will be screaming their hearts out to their top hits. If it's a really popular band, they will most definitely be Snapchatting the concert so all their friends know how cool they are. They'll probably buy a concert shirt to commemorate the event, and then wear it to school the next day.
4. The "awakening" fans
This category is an interesting one. These are people that are going to a concert of a band they've never heard of. Whether they were invited by a friend or they just love to try new things, these people are true concert fans. Assuming they enjoy themselves, they have a sort of "awakening" moment at the concert where they fall in love with the band. The next day they'll listen nonstop to all their music and maybe become a die hard fan, who knows.
5. The totally uninterested
These people are also extremely obvious to spot. Throughout the concert they will rarely smile. They were probably dragged to the concert by their friends or significant others. If the concert has seating they will probably not stand at all. If the concert is standing room only then they will most definitely not be dancing. Because they didn't want to go to the concert in the first place, they will be more annoyed at the things that normal concert fans overlook, like being shoved by strangers or having your seat kicked.