Phobias
Many people think Phobias are just fear that are more extreme. But phobias are indeed a type of Mental Illness. Because of this the person is too afraid to do certain things like fly in an airplane. This is called Aviophobia.
What causes a Phobia?
Phobias are usually caused by a traumatic thing in their childhood or later on in life. For example somebody with arachnophobia (fear of spiders) might have had a spider crawl on them and try to bite them. This is a good way for somebody to get arachnophobia. There's a myth saying that children get their parents phobias passed down to them. But like I said it is a myth and every being on earth has a different phobia then others.
More Examples of Phobias
Besides the two I mentioned before there are hundreds more phobias! Too many to list here! But some others include: Acrophobia-Fear of heights,Coulrophobia- Fear of clowns, and Cyclophobia-Fear of bicycles. Like I said before there are hundreds of phobias besides the five I mentioned! If you want the complete list here's the link! http://phobialist.com/#TOP