In this Adventure in Etymology we jot down a jot or two about jots (and tittles).
A jot [ʤɒt / ʤɑt] is:
The smallest letter or stroke of any writing; an iota.
A small, or the smallest, amount of a thing; a bit, a whit. E.g. He didn’t care a jot for his work.
A brief and hurriedly written note.
An instant, a moment. (obsolete)
And to jot (down) means:
to write (something) quickly; to make a brief note of (something). E.g. I will jot it down in my jotter.
It comes from Middle English jote (jot, tittle, whit), from Latin iōta (iota – a Greek letter), from Ancient Greek ἰῶτα (iôta – the 9th letter of the Ancient Greek alphabet (Ιι), a very small part of writing, a jot), from Phoenician 𐤉 (yodh / y – the 10th letter of the Phoenician abjad), ultimately from the Ancient Egytian hieroglyph 𓂝 (arm) [source].
Related words include jotter (a memordandum book, exercise book, someone who jots), jotting (a brief note or sketch), and jotty (written as, or like, a brief informal sketch) [source].
The expression (every) jot and tittle means a small detail, or the smallest details [source].
A tittle is any small dot, stroke, or diacritical mark, especially if part of a letter, or if a letter-like abbreviation; in particular, the dots over the Latin letters i and j. A small, insignificant amount (of something); a modicum or speck. [source].
Related words include tittle-tattle(r) (an idle gossip, a trifling talker, to engage in/spread gossip), tittle-tattling (idle gossip) title, and tilde (e.g. ~, as