what are cardinal vowels?describe and classify the english vowels?

Vowels in the English language are A, E, I, O, U, and
sometimes Y.

The term "cardinal vowels" is related to a
system created by Daniel Jones to classify the ways in which the parts of the mouth and
throat involved in articulation are shaped to make the different sounds associated with
those vowels, separately or in combinations. The voicing of vowels is affected by the
height of the space inside the mouth (between the roof of the mouth and the jaw), the
backness (where the tongue is placed during the pronunciation of the vowel), and the
roundedness (the shaping of the lips).

Because vowels in
English have many different sounds, depending upon their placement and combination with
other letters, it is not possible to give one all-encompassing classification of any
given vowel. The pronunciation depends upon too many variables.