Tit is the ninth letter of the Samaritan alphabet and carries the numeral value nine, the last of the units before the sequence moves to the tens. The name is the inherited Northwest Semitic one behind Hebrew tet, and the letter stands for what was an emphatic t in the older language, a consonant made differently from the plain t written by taaf at the end of the alphabet.
The word emphatic is a term of art rather than a description. In Arabic, which preserves the series clearly, the emphatic consonants are pronounced with the back of the tongue raised and they colour the vowels around them. In the reconstructed earlier stages of the family they may have been produced differently again. What the alphabet records is that the distinction existed and was worth a letter of its own; how it sounded to the people who first wrote it is a separate question from how it is read now.
Greek, adapting the alphabet, had no emphatic consonants and no use for the distinction, so it fitted the sign to an aspirated t and called it theta. The Greek letter kept the ninth position and the numeral value nine, so a Samaritan scribe and a Greek scribe writing the number nine in letters are using the same inherited sign.
The character is encoded at U+0808.