Crosswords are one of the most common types of word puzzle. The basic aim of a crossword is to place the correct combination of words into a grid. Words intersect each other at shared letters. Most crosswords provide the words to be placed by means of clues which must be solved to find the word.
The solution to each "clue" is an anagram of the actual word. In order to solve the word, one must first decipher the anagram to figure out the correct word.
A cryptic crossword is one which has cryptic clues. These clues are indirect, and often involve things such as anagrams, or words that are found in more than one piece from parts of the clue.
A fill-in crossword, also known as a crusadex or cruzadex, is unique because it provides no clues with its words, and only provides the words itself. The puzzle has to be solved by forming words together based on space and letter positioning. Often, these crosswords have a different layout and use a few longer words in order to aid in solving the puzzle.