UI is the point when interactions between machines and people happen. It lays down the parameters of a user's interaction with a machine.
Altcoin
Altcoin is the term given to describe alternative digital assets, such as a coin or token that is not Bitcoin. This nomenclature comes from the idea that Bitcoin is the original cryptocurrency and that all others are then considered “alternate” or “alternative” coins.
All network users can see on-chain transactions because they are recorded on the distributed ledger. Off-chain transactions, however, take place away from the blockchain network
Cryptocurrencies known as coins run on separate blockchains and are unrelated to other coins. Such a cryptocurrency's single unit is also known as a coin.