Convert yottabyte to byte

A bit is a single 0 or 1, and a byte is eight of them, 256 possible values, enough for one Latin letter: a byte has been 8 bits since the IBM System/360 of 1964, and 'octet' says so explicitly, which is why French writes Mo rather than MB. Bits are counted where single ones matter – 16-bit audio, 24-bit colour, 256-bit keys, internet speeds – and bytes where data is stored: an emoji takes 4 bytes in UTF-8, a photo a few million, a film a few billion. Lower-case b is bits, capital B bytes.