Open Your Umbrella Indoors Day is observed on March 13, 2021. On this day one should open an umbrella within closed buildings, although this is supposed to bring bad luck. Whether this superstition is true or not, can therefore be tested with the Open-Your-Umbrella-Indoors-Day. Introduced was the day in 2003 by Thomas Esward Knibb.
An umbrella or parasol is a canopy designed to protect against rain or sunlight. The word parasol usually refers to an item designed to protect from the sun; umbrella refers to a device more suited to protect from rain. Often the difference is the material; some parasols are not waterproof.
In Britain, umbrellas are sometimes referred to as "gamps" after the character Mrs. Gamp in the Charles Dickens novel Martin Chuzzlewit, although this usage is now obscure. Mrs. Gamp's character was well known for carrying an umbrella. Brolly is a slang word for umbrella, used often in Britain, New Zealand, Australia, South Africa, and Kenya. (With material from: Wikipedia)