If you've read any Shakespeare, you've read Early Modern English. Old English was a Western-Germanic language. A good example of Old English is Beowulf. Caution, Old English is extremely difficult to read.
It was the language spoken in England before the Normans invaded in 1066. Once the Normans took over the language of government became French. When a language is not the governing language, and not the language of print, then it lacks stability and shifts rapidly and become very regionally variable. English went through this for a little under 500 years. We do not know exactly what happened during this period linguistically, because English was not being written. However, when English again became the official language of England it was very different, and had incorporated a lot of French into its lexicon. Interestingly enough though, of the 100 most commonly used English words today 96 of them derive from Old English, 1 is French and 3 are Old Norse.