Frontness/backness is one of the three distinctive features of vowels. This blog post will explain the positions of the tongue, used in English, and list the English vowels at each degree.
The frontness or backness of a vowel is the location of the tongue in the mouth from back to front.
Front = front vowels are produced when the tip of the tongue is near the front of the mouth. Ex. cit(y), b(i)d, p(e)t, p(a)t, ch(a)otic
Central = central vowels are produced when the tongue is in a neutral position. Ex. b(u)d, (a)bove
Back = back vowels are produced when the back of the tongue is in the back of the mouth. Ex. h(oo)t, p(u)t, l(aw), f(a)ther, pill(ow)