Phonics
Appearance
Phonics is a way of learning to read by segmenting words to spell and blending sounds to read.
At the core of phonics is the phoneme. A phoneme is essentially a sound.
Representing a sound written down is a grapheme (in the early stages of a phonics programme you could say a grapheme is a letter but in reality a grapheme can represent multiple letters so a grapheme is more accurate to say.
The representation between a phoneme and a grapheme is called a GPC or Grapheme Phoneme Correspondence.
A phoneme can be made of one letter, two letters (a digraph) or three letters (a trigraph).
I am following Fast Phonics, Reading Eggs and Letters and Sounds.