Crossword Puzzles Basics

Crosswords Basics
A crossword is a word puzzle that normally takes the form of a square or rectangular grid of white and shaded squares. The goal is to fill the white squares with letters, forming words or phrases, by solving clues which lead to the answers. In languages that are written left-to-right, the answer words and phrases are placed in the grid from left to right and from top to bottom. The shaded squares are used to separate the words or phrases.

Squares in which answers begin are usually numbered. The clues are then referred to by these numbers and a direction, for example, "4-Across" or "20-Down". At the end of the clue the total number of letters is sometimes given, depending on the style of puzzle and country of publication. Some crosswords will also indicate the number of words in a given answer, should there be more than one.

Crossword Grids
Crossword grids such as those appearing in most North American newspapers and magazines feature solid areas of white squares. Every letter is checked, and usually each answer is required to contain at least three letters. In such puzzles shaded squares are traditionally limited to about one-sixth of the design. Crossword grids elsewhere, such as in the United Kingdom and Australia, have a lattice structure, with a higher percentage of shaded squares, leaving up to half the letters in an answer unchecked. For example, if the top row has an answer running all the way across, there will be no across answers in the second row.

Another tradition in puzzle design (in the United States and United Kingdom in particular) is that the grid should have 180-degree rotational symmetry, so that its pattern appears the same if the paper is turned upside down. Most puzzle designs also require that all white cells be connected in one mass through shared sides.
Crossword Grid Sizes
Puzzles are often one of several standard sizes. For example, many weekday puzzles (such as the New York Times crossword) are 15×15 squares, while weekend puzzles may be 21×21, 23×23, or 25×25. The New York Times puzzles also set a common pattern for American crosswords by increasing in difficulty throughout the week: the Monday puzzles are the easiest and the puzzles get harder until Saturday. The larger Sunday puzzle is approximately the same level of difficulty as a weekday-size Thursday puzzle. This has led U.S. solvers to use the day of the week as a shorthand when describing how hard a puzzle is: i.e., an easy puzzle may be referred to as a Monday or Tuesday, a medium-difficulty puzzle as a Wednesday and a truly difficult puzzle as a Saturday.

Crossword Clue Details
Typically clues appear outside the grid, divided into an Across list and a Down list; the first cell of each entry contains a number referenced by the clue lists. For example, the answer to a clue labeled "17-Down" is entered with the first letter in the cell numbered "17", proceeding down from there. Numbers are almost never repeated; numbered cells are labeled consecutively, usually from left to right across each row, starting with the top row and proceeding downward.

Capitalization of answer letters is conventionally ignored. This ensures a proper name can have its initial capital letter checked with a non-capitalizable letter in the intersecting clue.

In some crosswords, often called straight or quick, the clues are usually simple definitions for the answers. Some clues may feature anagrams, and these are usually explicitly described as such. Often, a straight clue is not in itself sufficient to distinguish between several possible answers (often synonyms), and the solver must make use of checks to establish the correct answer with certainty. In the hands of any but the most skilled constructors, the constraints of the American-style grid (in which every letter is checked) usually require a fair number of answers not to be dictionary words.

Crossword Themes
Many American crossword puzzles contain a "theme" consisting of a number of long entries (generally three to five in a standard 15×15-square "weekday"-size puzzle) that share some relationship, type of pun, or other element in common.

First Answers
In the 'Quick' crossword in the Daily Telegraph newspaper (Sunday and Daily, UK), it has become a convention also to make the first few words (usually two or three, but can be more) into a phrase. For example, "Dimmer, Allies" would make "Demoralise" or "You, ill, never, walk, alone" would become "You'll never walk alone". This generally aids solvers in that if they have one of the words then they can attempt to guess the phrase. This has also become popular among other United Kingdom newspapers.