VV: Onset, Nucleus, Coda (Reader Comments and Addenda)
Jacob Mattison reminds me that "sometimes w" has nothing to do with "cwm"; it's because the "w" in words like "cow" is an off-glide, the second part of a diphthong (much like the "y" in "toy"), and is thus contributing to a vowel sound. The point is still valid, though: in the linguistic sense, it's not letters that are vowels, but sounds. A letter can represent multiple sounds, and there are letters (notably y and w) that can represent either a consonant sound or a vowel sound.
(Last updated: 10 January 1999)