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