Find the virtual currencies other than bitcoin mining bitcoin exchanges in 2018. Bitcoin is decentralized, meaning no central authority or bank, controls the supply. It is controlled by people who run the software. Centralized coins, like Amazon coin, are controlled by the central authority or company that operates the coin.
In this case the central authority controls the supply. This is the terms given to coins based on the Bitcoin software. Since Bitcoin is open source anyone can take the code, change some things, and create another coin system. Generally, these coins depend on the Bitcoin developers to put out new versions of the software and they adapt it to whatever parameters they use. Proof of Work, Hashing Rate, and Difficulty.
Some coins use different proof of work algorithms so their hashing rate cannot be compared one-to-one. One scenario that has happened is that many people will start mining a specific coin, the hashing rate will rise and the difficulty goes up. If the exchange price of the coin drops for some reason they trade their coins and move their mining equipment to another coin. Now the difficulty is so high it takes weeks to solve the next section and all transactions stay in limbo. They create their own block chain ledger and create s situation where they can spend the same coins twice.
Or they can simply disrupt the whole system by delaying transactions. Some other coin could replace Bitcoin as the most popular virtual currency. However, if one of these Alt-coins does something better than Bitcoin it is possible that Bitcoin users could adopt this change within the Bitcoin system rather than switching to another coin. It remains to be seen what will happen.