Why is Ted short for Edward?

The nickname "Ted" for Edward has historical roots in the Old English tradition of letter swapping. During the Middle Ages, when there were a limited number of first names, people used letter swapping to differentiate individuals with the same name. In the case of names starting with a vowel, like Edward, it was common to replace the first letter with an easier-to-pronounce consonant. Thus, "Ed" became "Ted." Interestingly, "Ted" was already a popular nickname for "Theodore," making it one of the few nicknames derived from two different first names.