Why is there a dot on the letter 'I' and 'J'

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[chantonnn]

literally this is the best and most useful channel ever, I’m glad I found it, you go straight to the point and explain really well, thank u very much

[doodlegoat]

Elsewhere, the origin of the tittle has been put centuries earlier than what is claimed here.

[AlephSix]

The tittle is so useless to me. Because, in small print fonts like Roboto or Times New Roman, The i appears to look like the l.

Secondly, how does adding a tittle to BOTH i and j differentiate them at all. If anything, it just makes them also look like l.

And the only font it was useful in, is hardly ever used nowadays.