Digraph

A digraph is a combination of two letters used to represent one speech sound, that is a vowel or consonant. It can be considered as a two-letter phonogram.

Vowels

 * "ai" /eɪ/: afraid - aid - brain - chain - contain - detail - explain - fail - gain - mail - main -  pain - rain - train - wait
 * "ay" /eɪ/: always - away - day - delay - display - maybe - okay - pay - pray - play - say - stay - today - way
 * "au" /ɔː/: audience - author - autumn - caught - cause - daughter - fault - laundry - naughty - pause - taught
 * "aw" /ɔː/: awful - draw - drawer - law - lawyer - raw - withdraw
 * "ee" /iː/: agree - between - feel - free - keep - meet - need - see - seem - week
 * "ow" /aʊ/: allow - brown - cow - crown - down - flower - how - now - power (also /əʊ/ grow - know - low)
 * "oo" /uː/: boot - choose - cool - fool - loose - moon - pool - root - school - soon - tool (also /ʊ/ book - good - foot)

Magic e
Magic e can be thought of as part of a discontinuous digraph: aCe, eCe, iCe, oCe and uCe, where C is a consonant.
 * cake - complete - like - home - cute - include

Consonants

 * "ch" / tʃ/ as in much, child and also /k/ as in chemistry, psychology
 * "ng" /ŋ/ as in song, thing
 * "ph" /f/ as in phase, graph
 * "sh" /ʃ/ as in fish, ship
 * "ss" /s/ as in class, essay, princess
 * "th" /θ/ as in think, path and also /ð/ as in then, breathe
 * "zh" is sometimes used as in Dr. Zhivago. See IPA phoneme /ʒ/.

IPA
An IPA digraph is a combination of two IPA phonetic symbols that is regarded as a single phoneme.

The following are the IPA digraphs for English phonemes
 * dʒ tʃ aɪ aʊ eə eɪ ɪə ɔɪ əʊ ʊə

If the IPA long-vowel symbol is counted, we can add the following digraphs
 * ɑː iː ɔː uː ɜː

IPA phonetic sequence /juː/ is not regarded as a trigraph, but it is analized as /j/ and /uː/.