What is a crossword puzzle?

A crossword puzzle is simply a word puzzle that appears in the form of a rectangular grid, or a square, that features black shaded and white squares. The goal of the solver is to fill the white squares which in turn gives further hints to the other clues you must solve. The answer may run from left to right, and from top to bottom. The black shaded squares separate the answers. 

In North America the crosswords are generally free of black shaded squares, instead being solid with white squares. However, when black shaded squares are featured, they are limited to a sixth of the crossword design. Meanwhile, in the majority of other areas crosswords are crafted in a lattice structure which shades up to 50% of the area. 

Another puzzle designing tradition is radial symmetry, the pattern should appear the same when turned upside down. Additionally, the majority of puzzle designs require the white cells to be connected in one mass. 

Japanese crossword puzzles follow two additional rules: shades cells cannot share a side, and all corner squares must be white. 

While the Swedish style grid does not use clue numbers, instead the clues are within the cells that are normally, in other countries, shaded. There are arrows which indicate whether the clue should be answered horizontally, or vertically. This grid is used in a number of countries, and is generally found in A4 sizes magazine, or in daily newspapers. They frequently feature pictures where the normal black shaded squares are. Most of the time the puzzle follows a common theme. 

There are a number of standard sizes when it comes to crossword puzzles. Weekday puzzles are often 15x15 squares, with weekend puzzles being anywhere from 21x21 to 25x25. Additionally, many American crosswords increase in difficulty as the week moves, with Monday puzzles being simple and straightforward in comparison to the extreme difficult of the Saturday puzzle. Many times the Sunday puzzle is a larger version of a Thursday puzzle. Using this description, we can determine that Mondays and Tuesdays are easy puzzles, with Wednesday being of medium difficulty as we reach Saturday, the most challenging of them all. 

The smallest crossword in publication is the 4x4 that John Wilmes complies daily for distribution by USA Today, and The Universal Uclick

Clues generally appear outside of the grid, to the side of the puzzle, divided into two lists. Clues are split into across and down, and feature numbers which correlate to a row on the grid itself. If a clue is labelled 3 down, then the first letter belongs in the cell that is marked 3 and the direction is down. Numbers are not repeated, so they generally follow an even number for across, and odd numbers for clues in the down column. Though, in Japan crosswords are frequently numbered top to bottom from left to right.