Why is the word I capitalised in English?

Largely for practical reasons of legibility, dating from medieval manuscripts — not out of any sense of self-importance, which is the explanation people usually reach for.

English is the only major language that capitalises its first-person singular pronoun as standard. German capitalises the formal Sie for "you", and all its nouns, but not ich.

The word descends from Old English ic, which was not capitalised. As English evolved, the pronunciation shifted and the written form shortened to a single letter, i.

That created a problem. In the handwriting of the period, a lone lowercase i was a small stroke easily lost among the surrounding letters, or mistaken for part of an adjacent word. Manuscripts show scribes experimenting with solutions — lengthening the stroke, adding a mark above it. The mark placed over the letter to distinguish it is, incidentally, where the modern dot on a lowercase i comes from.

Capitalising it solved the same problem more decisively. The practice appears from around the thirteenth and fourteenth centuries, becoming standard by the time printing fixed English orthography.

So the capital is essentially a typographic fix that became a rule.

A related question is why English does not capitalise you, he or she. Those words were never reduced to a single letter, so they never presented the same legibility problem.

English once had a second-person distinction — thou for singular and informal, you for plural and formal — and lost it, keeping only you. Neither was capitalised.

In some religious writing, pronouns referring to God are capitalised. That is a convention of reverence, and a genuinely different reason from the one behind I.