The Alphabet is composed of vowels and consonant letters.
Consonant Blends is when 2 or 3 consonants stay in a cluster, so they are read together.
Digraphs are when 2 consonants come together and make 1 sound; complex consonants are when consonant letters are combined and pronounced as a single sound.
Silent Letters are letters that, in a particular word don't correspond to any sound in the word's pronunciation.