Encoding in Phonics is the process of hearing (or mentally verbalizing) an individual spoken sound and then recalling and writing down the letter or letters that are used to spell the sound.
This process is called encoding because the letters of the alphabet are a symbolic code for the spoken sounds in English. So when we write, we are converting auditory information into coded visual information.
Encoding can also mean spelling a whole word in synthetic phonics. However, to spell a word using phonics, a child needs to segment the word first in order to identify the individual sounds that make it up.
Encoding in English isn’t straightforward because most sounds (phonemes) can be represented by different combinations of letters (graphemes) in different words. For instance, the highlighted letters in the following words all represent the same sounds:
apron, rain, play, snake, eight, obey
Click on the following link for a complete list of the phonemes in English and the letters used to represent them.