What is phonics?

Phonics is the relationship between a specific letter and its sound, only as it relates to the written word. Phonics is used, for example, when a reader comes across an unknown word.

Phonics is also used in writing, or encoding text. For instance, if a child is trying to spell smart, she might begin with the /s/ sound and write s. Then, she goes to the next sound/m/ and writes m, and so on.

http://www.nwrel.org/learns/resources/toolkit/NationalReadingPanel_FAQ.pdf