Superstition is a belief, which is not based on reason.
It is illogical.
For instance, while stepping out of home, if you encounter a black cat, you may feel it as bad omen.
A part of your mind tells you there is no reason and logic behind your fear. Cats do not have the ability to cause you harm. Yet, you try some ritual to neutralize this fear, like praying to god or returning to home.
Superstitions in human beings are not unusual.
They are quite common.
Very few people are an exception from superstitions. Superstitions may vary from place to place, but some superstitions are particular to certain locations.