Consonants - a consonant is a speech sound. There are 21 consonant letters in the English alphabet. They are: B, C, D, F, G, H, J, K, L, M, N, P, Q, R, S, T, V, W, X, Y, Z
(A, E, I, O, U are vowels)
Adjacent Consonants - are two or more consonants that appear next to one another within a word and they represent a different sound. e.g. stop - the 'st' are adjacent consonants because they appear next to each other and but also they spell two different sounds. /s/ and /t/.
Adjacent consonants can appear at the beginning of words e.g. 'grab', at the end of a word e.g. 'bend' or at both ends of a word e.g. 'print'
Consonant strings - when there are more than two consonants next to each other e.g. 'string'