Even though a type of word puzzle was found inscribed on the wall of an ancient Egyptian tomb, the first known crossword puzzles are credited to journalist Arthur Wynne, who designed his ‘word-cross’ in 1913. Wynne’s puzzle appeared in a Sunday newspaper called New York World.

Since its inception, the crossword puzzle has become one of the world’s most recognizable puzzles, attracting enthusiasts from all over the world, and now appearing in virtually all newspapers.

Crossword puzzles are word games in which the answers correspond to numbered clues. The words are put into a grid of horizontal and vertical squares to form completed, intersecting words. When all of the words are supplied correctly, the puzzle is complete. In North America and Great Britain, crossword grids traditionally have 180-degree rotational symmetry. The diagram, or placement of black squares within the grid, must be symmetric diagonally. This means that the pattern of the puzzle will appear the same if the puzzle is turned upside down.

American crossword puzzles conform to a set of established rules made popular by publisher Simon & Schuster, the original crossword puzzle publisher. The standard puzzle grid size is 15x15. However, 17x17, 19x19 and 21x21 also are used. Smaller 13x13 also are accepted. Many crossword puzzles do not use two-letter words, and three-letter words are kept to a minimum. In addition, every letter square must be part of both an Across and a Down word. Crossword rules are different in other parts of the world. For example, in Japan, the corner squares of a crossword puzzle must be white.

Despite once publishing a statement describing crosswords as a ‘sinful waste in the utterly futile finding of words the letters of which will fit into a prearranged pattern’ in 1924, The New York Times routinely produces what many consider to be the world’s most challenging crossword puzzles. Stanley Newman is credited with completing a New York Times crossword faster than anyone in history. In 1996, Newman completed a crossword in two minutes, 14 seconds.

Crossword puzzles appear in newspapers, magazines and kids’ activity books and are even used in school lessons to supplement vocabulary lessons. Doing these puzzles also may be good for one’s health. According to a University of California at Berkeley study, crossword puzzles may help in the fight against Alzheimer’s disease. Researchers found that the more often someone engaged in mentally stimulating activities such as crosswords, the less buildup of beta-amyloid plaques in the brain, which are hallmarks of the disease. Doing crossword puzzles also may offer a distraction that helps people reduce stress.

Crossword puzzles have a storied history. They are completed recreationally and in competitions, and cruciverbalists look forward to new puzzles in their newspapers every week.