Q, J, Z, and X are the alphabet letters that are used the least frequently in English. Less than 1% of the vocabulary in English uses each of these letters. The least frequent letter among these to begin words is X.
The English language uses the letter E the most frequently, in contrast. It appears in words in more than 11% of all words. Not far behind are the letters R, N, T, and S, with S being the most frequent letter at the beginning of words.
The letter U appears the least frequently among the vowels, which are all used pretty regularly.