If you've got five minutes to spare, you might like to look at a short BBC video (or slideshow, rather) on the history of writing and alphabets, narrated by Dr James Clackson from the Classics department of Cambridge University. We are shown examples of writing dating back thousands of years - from Mesopotamia (present-day Iraq), Ugarit (present-day Syria), China, ancient Egypt and Central America (the Mayan civilisation) - as well as the more recent Latin and Greek alphabets.
The video includes pictures of baked clay tablets from Mesopotamia with the earliest (5,000 years ago) proto-writing (literally 'approaching writing') -- figures and drawings, rather than letters as such. These tablets were often used for accounting purposes - to record how much barley someone had, for instance. The video then jumps 2000 years to show examples of cuneiform (wedge-shaped) writing written on basalt stone. The Ugarit script looks cuneiform in style, but it consists of far fewer symbols than previously, an indication that an alphabet is being formed rather than a situation where a symbol represents a whole word or phrase.
In China the earliest examples of writing are complete sentences written on pieces of bone. Then, Mayan glyphs, including examples written on a cocoa cup, can be seen. There are also slides of Egyptian hieroglyphs written on papyrus. The first alphabet to have signs for vowels was the Greek alphabet. This alphabet was borrowed by the Romans, and that is what we use today (those of us who speak a language that uses the Latin alphabet, like English).
The slideshow, with narration, is here.