We often say that things are 'as easy as ABC', but if it hadn't been for the Phoenicians, we might not have an alphabet at all. And without the ancient Greeks - who adapted the Phoenician alphabet before passing it on to us - all our letters would would be back to front.
It is thought that the Greeks first encountered the alphabet around 1000 BC through trade with the Phoenicians, who inhabited what is now Lebanon. The Phoenicians wrote from right to left. When the Greeks borrowed their script, they experimented with boustrophedon (meaning 'plough-wise') writing: changing direction line by line, like an ox pulling a plough. Eventually, the Greeks settled on writing from left to right, and so their letters were mirror images of the Phoenician originals.
To adapt the alphabet to their own needs, the Greeks had to use some of the Phoenician letters in a different way. The Phoenicians only wrote down their consonants, leaving the reader to fill in the vowel sounds. But vowels had a far greater significance in Greek - for example, certain words could only be distinguished from others by placing the correct vowel at the beginning.
Fortunately, Phoenician had several letters for consonant sounds that were not used in the Greek language, so the Greeks used these letters for vowels. The order of the Phoenician alphabet was, by and large, kept on, as were most of the names of the letters: aleph, beth and gimel for example, became alpha, beta and gamma. The Romans, in turn, adapted the Greek alphabet for the Latin language, and are responsible for the shape of the alphabet as we know today.