"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."( Matt 5:18, KJV)

"I tell you the truth, until heaven and earth disappear, not the smallest letter, not the least stroke of a pen, will by any means disappear from the Law until everything is accomplished." (Matt 5:18, NIV)

I don’t know a believer who hasn’t heard the phrase ‘jot or tittle’. Preachers must think it sounds cool or that it has a certain rhythm to it, kind of a catchy type thing, buzz word, or something. In fact, I heard it mentioned so many times that I was shocked, discovering that it appears only once in the Bible.

THE JOT
According to Strongs 2503, a ‘jot’ is the tenth letter of the Hebrew alphabet.

I've posted the Hebrew Alphabet so you can follow along with me. Hebrew reads from right to left so we want to go to the top of the columns on the right. Alef is the 1st letter of the Hebrew Alphabet, Bet/Vet the 2nd (as I've outlined in 'black'), Gimel is the 3rd, Dalet 4th, Hay 5th, Vav 6th, Zayin 7th, Het 8th, Tet 9th, and Yod 10th (as I've outlined in 'Blue'). Therefore a jot is the letter Yod, which is the smallest letter in the Hebrew alphabet.

THE TITTLE
The Bet/Vet and the Kaf/Haf ('green' outline) look very similar except that the Bet/Vet has a little extension on its bottom/right corner. Likewise the Dalet and the Resh ('red' outline), the Dalet with a little extension on its top/right corner. Also the Het and Tav ('purple' outline), the Tav's bottom/left corner is extended.

These small extensions are called tittles.