U

UI (User Interface)

The interface and its layout, where a user operates. The connection between the user and software.

Uncle/ Uncle block

Stale blocks that contribute to the security of the main chain.

Unit of Account

A primary measurement of money, both fiat and cryptocurrencies.

UNIX

An operating system similar to DOS and Windows, supporting multiple concurrent users.

Unix Epoch Time

Describes the time passed till a certain point in time, e.g. till today at 8 a.m. It is calculated in seconds minus leap seconds since the Unix Epoch, which was at 00:00:00 UTC on 1st January 1970. Unix Epoch Time is usually represented as `timestamp` as a simple integer.

Utility token

A token aimed at accessing a specific product and also used in the ICOs processes.

UTXO

Stands for Unspent Transaction Output – a method of spending from the leftover outputs of a previous transaction so that new outputs are created for future transactions. The excess coins are sent to a self-controlled address.