Twelve keys, twenty-six letters. The keys 2 to 9 carry three or four letters each, and you pressed it once, twice or three times to get the one you wanted: S was the 7 key, four times. Practised thumbs did it without looking.

Predictive text cut the work. You pressed each key just once and the phone looked the sequence up in its dictionary: 4-6-6-3 could be good, home or gone, and the star key stepped through the guesses.

A text message holds 160 characters. The length was settled in the mid-1980s by Friedhelm Hillebrand, who checked how long postcards and telex messages usually ran. The first text message went out in December 1992 and said “Merry Christmas”, sent from a computer to a phone.

Late-1990s phones came with small games built in. The one where a worm eats dots and grows longer became so familiar that people still recognise it from four arrow presses.