The check or check mark (American English), checkmark (Philippine English), tickmark (Indian English) or tick (Australian, New Zealand and British English) is a mark (✓, ✔, etc.) used in many countries, including the English-speaking world, to indicate the concept "yes" (e.g. "yes; this has been verified", "yes; that is the correct answer", "yes; this has been completed", or "yes; this [item or option] applies").

The X mark is also sometimes used for this purpose (most notably on election ballot papers, e.g. in the United Kingdom), but otherwise usually indicates "no", incorrectness, or failure. One of the earliest usages of a check mark as an indication of completion is on ancient Babylonian tablets "where small indentations were sometimes made with a stylus, usually placed at the left of a worker's name, presumably to indicate whether the listed ration has been issued."

As a verb, to check (off) means to add such a mark. Printed forms, printed documents, and computer software (see checkbox) commonly include squares in which to place check marks.

The check mark is a predominant affirmative symbol of convenience in the English-speaking world because of its instant and simple composition. In other language communities, there may be different conventions.

It is common in Swedish and Norwegian schools for a ✓ to indicate that an answer is incorrect, while "R", from the Swedish rätt or Norwegian riktig, i.e., "correct", is used to indicate that an answer is correct.

In Finnish, ✓ stands for väärin, i.e., "wrong", due to its similarity to a slanted v.^{[citation needed]} The opposite, "correct", is marked with ${\displaystyle \cdot \!/\!\cdot }$, a slanted vertical line emphasized with two dots (see also commercial minus sign).

In Japan, the O mark is used instead of the check mark, and the X or ✓ mark are commonly used for wrong.

In the Netherlands (and former Dutch colonies) the flourish of approval (or krul) is used for approving a section or sum.