History of the Alphabet
The earliest alphabetic writing (about 1800 BC, Egypt)
About 1800 BC, some people from Canaan (modern Israel and Lebanon) traveled down to northern Egypt to trade and to work in the turquoise mines at Serabit. They built a big temple to the Egyptian goddess Hathor, whom they called Baalat or The Lady (the feminine form of Baal, meaning Lord), so they could sacrifice and pray there. These Canaanites didn't know how to read or write, but when they saw Egyptian hieroglyphs, they got interested in writing down their own language. They used simple versions of the Egyptian hieroglyphs to stand for sounds in their own language - Aramaic.
The Canaanite miners at Serabit called the first letter "Alp", meaning "ox" in Aramaic. The letter looked like the head of an ox, with little horns. Today we turn it upside down and it's the letter A (aleph, in Hebrew; alpha, in Greek). They called the second letter "Bet", meaning "house" in Aramaic. It looked like a drawing of a house. That's our letter B (bet in Hebrew, beta in Greek).