Anxiety is that feeling you get in your gut right before something that worries you is about to take place. A lot of people worry for no reason, just expecting the worst of everything to happen. Others just get nervous of being judged by others and sticking out like a sore thumb.
Anxiety itself is normal, but there are disorders linked to anxiety that can last far longer than just a typical case of anxiety.
It's a completely natural feeling and it comes from our desire to fit in and feel safe. Whenever we feel like we're not going to fit in, make a fool of ourselves, or put ourselves in danger, it's a natural reaction to either avoid the scenario or worry about the day it comes.
For example, one of the most popular cases of anxiety is test anxiety, in which you feel stressed out about bombing the test and getting a lousy score.
Anxiety, despite being felt in the gut, originates in the brain. Parts of the brain trigger the fight or flight response, which is an evolutionary trait of our brains to help us survive comfortably.