At the beginning of the cryptocurrency industry, bitcoin was the only one available. Although it is still the largest by a very big margin, there are hundreds if not thousands of coins that are trying to catch up. From Ethereum to Bitcoin Cash to Particl and many more, the market has become flooded by these altcoins or alternative coins.
Although it may seem like it, the majority of these coins are not in competition with each other. Rather, each one of them does a separate task and asks for separate things with its purchasing. There are two main types of coins, those being public and private. Public coins have a higher degree of anonymity while private coins are usually just used internally.
The underlying blockchain technology is what fuels all of these alt coins and bitcoin itself. The technology essentially is a distributed ledger that bounces between the network of computers to create an immutable base of transactions that is anonymous as well as completely transparent.
Public coins have used traceability to ensure that the coins are as transparent as possible. When conducting transactions with a public coin, anyone can see what the transaction is and essentially have access to the blockchain that it lies on. Privacy coins use the opposite and focus on various stealth tactics to ensure that those characteristics do not apply. Some view private coins as a little bit sketchier given the need for anonymity and no traceability.
The privacy that one desires comes with the network of cryptography that most cryptocurrencies use today. This helps to ensure anonymity and pseudonymity. These people are happy with being public, but still do not share their personal information with anyone.
In the world of cryptocurrency, some find it to be slightly illegitimate given the need for anonymity but in order for it to survive, it must break this notion and find some sort of legitimacy.