This is a group of related languages that includes Arabic and Hebrew. They are related to some very early languages dating from 2500 BC or earlier and written in Sumerian cuneiform. Later Semitic languages were written in the Ugaritic, Phoenician, Aramaic, Hebrew, Syriac and Arabic alphabets.
The word “Semitic” comes from Shem, one of Noah’s three sons. Shem was the father of Aram, Asshur, and Arpachshad (Genesis 10:21-31) who were the ancestors of the Arabs, Aramaeans, Assyrians, Babylonians, Chaldeans, Sabaeans, and Hebrews. Consequently, the language family of these people was called “Semitic”. However, Shem was also the father of Elam and Lud (Genesis 10:22) from whom the Elamites and Lydians were descended, and they did not spoke Semitic languages. The Canaanites and Amorites also spoke Semitic languages, although they were descendants of Ham (Genesis 10:6).
See the Wikipedia article on Semitic languages for further information