The Chronicles (there are more than one) were developed primarily as a means of remembering and recording the date. There was a widespread contemporary belief that the world would end at the millennium (1000 A.D.), so fixing your place relative to the end of the world was important. Annals were mainly kept at monasteries and were intensely local documents. Items important to the locals, such as the fertility of the harvest or the paucity of bees, would be eagerly recorded, wheras distant political events were largely ignored. A combination of the individual annals allows us to develop an overall picture, a document that was the first continuous history written by Europeans in their own language. Thus the Chronicles are an important development in historiography as well as a useful historical documents in their own right.
There are seven surviving manuscripts, of which six are written entirely in Old English, while the seventh is a mixture of Old English and Latin. The oldest (Corp. Chris. MS 173) is known as the Parker Chronicle, after Matthew Parker who once owned it, or the Winchester Chronicle.
Some think that the chronicles were originally commissioned by King Alfred, but there is no substantive evidence for this. Many of the surviving manuscripts that are together known as The Anglo-Saxon Chronicles are concerned with him, but others marginalise him, depending on the preference of the original scribe. The translated texts (together with explanatory materials) are available in books and on the Internet, so scholars at all levels can now consult them directly.