If you could time-travel to the next millennium, A.D. 3000, do you think you’d understand English speakers living right where you live now? Linguists are of different opinions about this.
But keep in mind that a thousand years ago the language of England was Old English, also called Anglo-Saxon. Here’s a sample from one of the earliest pieces of writing in Old English, a poem called Beowulf: “Nu ic, Beowulf, pec... secg betsta, je for sunu wylle freogan on ferhpe.” What does it say? “Now, Beowulf, thee of heroes best, I shall heartily love as mine own, my son.”
Clearly, English has changed a great deal in the past thousand years. It has also changed in the past hundred years. Languages are always changing because people are always changing. Some changes are as simple as new words being coined for new things, like e-mail. Others are as profound as the shift from Old English to Middle English to modern English.