Tether is a cryptocurrency launched in 2014. It is a so-called stablecoin currently leading by market capitalization. Although according to the initial idea, each Tether was backed by $1 (that was going to keep the price of Tether stable), the company not always managed to maintain this price (at some point in October 2018 the price dropped to $0.9 per one Tether). Tether succeeds in terms of market capitalization and its price is almost all the time is really close to $1.
ABBC is a blockchain platform that enables secure payment transactions, helping to facilitate retail adoption of cryptocurrencies and make shopping online with digital assets a safer, more enjoyable experience for end-users.
Bitcoin Gold (BTG) is a Bitcoin hard fork that took place in 2017. The initial goal behind creation of Bitcoin Gold was to increase level of decentralization of Bitcoin network as it became obvious that most of the network is controlled by few mining pools.