Wei pertains to the smallest denomination of the cryptocurrency, Ether (ETH).
One Ether is equivalent to 1,000,000,000,000,000,000 Wei.
The term “Wei” was taken from one Wei Dan, a cryptography activist who is recognized for supporting the widespread use of strong cryptocurrency and privacy-oriented technologies.
Such breaking down of coins into smaller units was done so that the quantity of transactions may be precisely determined. Also, those rendered in smaller fractions or units are converted effectively to higher values in U.S. Dollars as with other fiat currencies for that matter. The new smaller units have been created and named for the proper identification of and support for the transactions done through the coins.