A tittle is a small distinguishing mark, such as a diacritic or the dot on a lowercase i or j. The tittle is an integral part of the glyph of i and j, but diacritic dots can appear over other letters in various languages. In most languages, the tittle of i or j is omitted when a diacritic is placed in the tittle's usual position (as í or ĵ), but not when the diacritic appears elsewhere (as į, ɉ).

The tittle first appeared in Latin manuscripts in the 11th century, to distinguish the letter i from strokes of nearby letters.^{[citation needed]} Although originally a larger mark, it was reduced to a dot when Roman-style typefaces were introduced.

The word tittle is rarely used. Its most prominent occurrence is in the introduction to the Antithesis of the Law in the Gospel of Matthew (5:18): "For verily I say unto you, Till heaven and earth pass, one jot or one tittle shall in no wise pass from the law, till all be fulfilled" (KJV). The quotation uses them as an example of extremely minor details. The phrase "jot and tittle" indicates that every small detail has received attention.