Kaph is the eleventh letter of the Syriac abjad and the first of the tens, with the numeral value twenty. It writes k and is one of the six letters with hard and soft readings; soft kaph is the voiceless velar fricative heard in the Scottish pronunciation of loch.
It joins on both sides and changes shape markedly at the end of a word, where in the Serto hand it drops a long tail below the line. Syriac has no separate final letters of the kind Hebrew developed; what it has is positional forms, so a final kaph is the same letter drawn as the last member of a connected run rather than a different character.
Its name is the inherited Northwest Semitic word for the palm of the hand, a gloss that describes a sign of the older linear alphabet and no longer describes anything in the Syriac form.
Kaph carries a good deal of grammar. It writes the second person pronominal suffix, the your or you attached to the end of a noun or a verb, so a reader meets it at the close of a word constantly, in exactly the position where its long tailed form appears. That combination, a very common grammatical ending written by a letter with a conspicuous final shape, makes kaph one of the easiest letters to pick out of a page of Serto at a glance.