Do you dread Friday the 13th? Does it freak you out if a black cat crosses your path? Will you pick up a coin on the sidewalk if you find it tails-side up? If you open an umbrella indoors, will everyone in the house experience bad luck?

If you put stock in any of these popular ideas, you may be a bit superstitious. A superstition is usually defined as an irrational practice or belief that stems from ignorance, fear, belief in the supernatural or a mistaken understanding of the cause of an event. Superstitions typically take the form of a belief that doing something—or not doing something—will result in particularly good or bad luck.

For example, many people believe that finding a four-leaf clover will lead to a streak of good luck for the finder. On the other hand, many people believe that walking under a stepladder or breaking a mirror will lead to bad luck.

Superstitions have been around for thousands of years. In fact, most superstitions can be traced back to ancient times, before science had developed to the point where people could find reasonable, scientific explanations for what they saw in the world.

Without the benefit of science and more advanced technology, ancient peoples would develop stories and beliefs to help them make sense of the world around them. Even though many superstitions have been refuted — or are just too strange to be believed — millions of people all over the world still follow them.

Take the umbrella, for example. If you were to carry one with you and open it indoors at random times over the course of a week, you'd probably be surprised by how many people mention that it's bad luck to do so! Why is that?

The humble umbrella — also known in various locales as a parasol, brolly, rainshade, sunshade, gamp or bumbershoot — takes its name from the Latin word umbra, which means shade or shadow. People have believed for hundreds of years that opening an umbrella indoors will result in bad luck “raining" down on you. There are a couple of theories about how this belief got started…

Some people believe the umbrella superstition comes from ancient Egypt, where the umbrella was primarily used for protection from the hot rays of the sun. Legend has it that ancient Egyptians believed that opening an umbrella indoors — away from the sun — was a disrespectful act that would anger the sun god, who would then take out his anger on everyone in the house in which the umbrella had been opened.

Others believe the umbrella superstition has a more modern — and practical — source. The first modern umbrellas were not all that safe. Built with hard metal spokes and spring triggers, they could be dangerous to open. In fact, opening one indoors could pose a danger to people and fragile objects nearby.

Warning people not to open an umbrella indoors served to protect the health and safety of people and property indoors. In this sense, the superstition might have stemmed from the “bad luck" — the injuries and broken objects — that often coincided with the umbrella's opening. To the extent that injuries were avoided, this superstition wasn't necessarily all bad!

Interestingly, some people believe that it's not always bad luck to open an umbrella indoors. Some people believe it's only bad luck if the umbrella is black, was a gift, has never been used outdoors, or there's a sick person in the house!

Other bad luck umbrella superstitions: