The fear of Friday the 13th is known as paraskevidekatriaphobia. While this superstition has led to popular beliefs about bad luck, it's not supported by any scientific evidence.
Opening an umbrella indoors is said to be bad luck but the truth is that doing so could cause injury or damage in confined spaces.
Black cats are often associated with superstitions, but these beliefs vary by culture. In many societies, black cats are considered symbols of good luck and protection.
Avoiding walking under a ladder is more about safety than superstition. Walking under it could be hazardous if something were to fall from it, but it's not inherently unlucky.
The idea that breaking a mirror leads to seven years of bad luck is a superstition without a factual basis.