Most tents are designed with camping in mind, but many people going to festivals use them as their temporary shelter.
In addition, festival goers have a different set of criteria to consider than campers.
Typically most festivals are in the summer.
With summer camping you aren't necessarily looking for something to keep you extra warm.
You're looking for something to keep the rain out.
One of the most important parts in regards to rain is having the seams sealed.
Some tents come with factory sealed seams while others should be sealed once you get them.
The biggest consideration is what kind of festival you will be attending.
If you are going to a rock festival there is a good chance you won't be spending much time in the tent anyway so a small tent will do just fine.
If you're participating in a renaissance festival you have several other considerations.
You may need to have several different outfits to change in and out of.
Additionally, many of these festivals last two weeks or more.
You will probably want to get a larger tent.
Don't just look at square footage.
You will probably also want to get a square tent as opposed to a dome tent.
The square tent will give you a larger square footage range to walk around in.
If you will be spending lots of time with changing costumes you will want to make sure you get a large square tent.
Lastly, you will want to consider getting a footprint for your tent on a rough surface.
The footprint is used to protect the tent from abrasion.
If the grounds will be soft grass then you can probably be safe without the footprint.