Silent and invisible letters in English

Silent letters constitute a notorious phenomenon in English: in wréstle, for example, only four out of the seven letters are actually sounded (*résl), and there can be strings of them in place names, exemplified by the trio Léicester, Glóucester, Worcester (*Léster *Glóster *Wùster). (The accents show stress and pronunciation, see English phonemes.)

But redundant letters can serve to distinguish between words that sound the same:

knôw knowledge = nô negative

knót tie = nót negative

wráp parcel = ráp knock, talk

wrîte read = rîght correct = rîte ritual

chéck verify = BrE chéque money

Typical silent letters are b finally after m or before final t (-mb -bt); g or k initially before n (gn-, kn-); gh finally or before final t ( -gh -ght); l after à and before final f or m (-lf -lm); n finally after m (-mn).