Fill-Ins, also known as Fill-It-Ins or Word Fill-Ins, are a variation of the common crossword puzzle in which words, rather than clues, are given, and the solver must work out where to place them. Fill-Ins are common in puzzle magazines along with word searches, cryptograms, and other logic puzzles. Some people consider Fill-Ins to be an easier version of the crossword. Since the Fill-In requires no outside knowledge of specific subjects, one can solve the puzzle in another language.

Solving a Fill-In usually requires trial-and-error. Many times, a first word is already given to help the solver start, but some difficult puzzles require the solver to begin from scratch without any help. Word entries are listed alphabetically by number of letters.