Yotta is the largest unit prefix in the International System of Units (SI), denoting a factor of 1024 or 1000000000000000000000000. It has the unit symbol Y. The prefix name is derived from the Greekοκτώ (októ), meaning eight, because it is equal to 10008. It was added to the SI in 1991.
A 200 ml glass of water contains 6.66 Y water molecules.
One yottabyte is a unit of information or computer storage that is exactly 1 septillion bytes. The yobibyte (YiB) is a related unit that uses a binary prefix, and means 10248 bytes (which is approximately 1.2 septillion bytes).