Letters, Sounds And Aspects Of Phase One
The DFES letters and sounds document (click to download) is a free document which has stood the test of time.
Published in 2007 it has withstood 3 governments and continues to be an effective tool when teaching phonics.
It is NON-STATUTORY guidance, i.e. you do not legally need to follow it.
It introduced the teaching sequence for phonics:
Review - Teach - Practice - Apply
And it is split into 6 distinct phases: