W is a ligature of “vv” which turned into a distict letter, similar to how “ae” turned into the letter æ. New letters in latin scripts seem to have evolved from

W is a ligature of “vv” which turned into a distict letter, similar to how “ae” turned into the letter æ. New letters in latin scripts seem to have evolved from either diacritics or ligatures. There are a few examples of letters borrowed from non-latin alphabets like þ in Old English