A tick (known as a checkmark or check in American English) is a mark (✓, ✔, ☑, , etc.) used to indicate the concept "yes", for example "yes; this has been verified" or, "yes; that is the correct answer". Its opposite is the cross, although the cross can also be positive (most notably on election ballot papers).
As a verb, to tick (off) or to check (off) means to add such a mark. It is quite common, especially on printed forms, printed documents, and computers (see check box), for there to be squares in which to place ticks. In America and Germany, it is more common for people to check a square box with an x mark; while in some European countries, it is more common for people to check a square box with a v-shaped checkmark.
In the U.S. (but not Canada) and some European countries (e.g. Finland and Sweden), the tick can be used as an error mark and indicates "no" rather than "yes". In Japan and Korea, an "O Mark" (in the appearance of a circle, unicode symbol "◯"), also known as "丸印" marujirushi, is used instead of a tick to mean 'yes'.
Another history suggests that it comes from the use of fountain pens. A fountain pen (a "self-filling pen" not a dip pen or a quill pen) would not always start flowing ink without some initial action. The downstroke of the pen's nib was enough to get the ink flowing and then the ink was available for the upstroke.
|Symbol||Unicode Codepoint (Hex)||Name|
|✓||U+2713||CHECK MARK (tick)|
|✔||U+2714||HEAVY CHECK MARK (bold tick)|
|☐||U+2610||BALLOT BOX (square)|
|☑||U+2611||BALLOT BOX WITH CHECK (square with tick)|