Word search
A word search is a puzzle in which the words from a given list are hidden inside a grid of letters, each running in an unbroken straight line, and the solver's job is to find and mark every one.
How many directions are allowed sets the difficulty. An easy grid runs its words left to right and top to bottom only. A hard one adds diagonals and allows every direction to run backwards, which gives eight bearings to scan instead of two. The squares that are not part of a hidden word are filled with letters chosen to look plausible, and words are usually allowed to cross and share a letter.
The puzzle is unusually welcoming because it demands no vocabulary and no general knowledge. You are given the words; the task is purely visual search. That also makes it one of the few puzzles that works identically in any language and at any reading age.
Norman E. Gibat is generally credited with printing the first one, in the Selenby Digest in Norman, Oklahoma, in 1968. A common variant uses the leftover letters — the ones no hidden word claims — to spell a bonus message, so the grid has a second answer after the list is complete.
Daily Word Search — the words you find complete a quotation; there is a large print edition too.