A crossword is a word puzzle that usually takes the form of a square or a rectangular grid of white-and black-shaded squares. The game's 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.
Written by Margaret Petherbridge, the crossword puzzle book sold for $1.35 and came with a pencil attached.
According to wikipedia