I once claimed that there are only two main blockchain or coins that I do not consider as “Alt Coins.” One of those coins is Bitcoin and the other is Ethereum. I feel this way because they are the two chains that started Peer to Peer cryptographic currency (in Bitcoin) and a decentralized chain capable of running apps (Called Dapps) on the chain. Basically, Ethereum is decentralized web OS fueled by miners mining ETH or other ERC20 Tokens.
The main thing that separates ETH from BTC is the ability to create Dapps on the chain. These Dapps can be anything from ERC20 tokens (cryptocurrency made off the Ethereum chain) to games that run off the ETH network. Etherium is the first of its kind prompting other like Tron to follow in its footsteps (although there are differences in the two.)
ETH was launched July 30th 2015 and is one of the newer coins in the top 10. It so innovative is held the number 2 spot for almost 3 years dropping to 3 on rare occasions to Ripple. Original authors of the ETH whitepaper include prodigy Vitalik Buterin, who is a genius in his own right, Gavin Wood, and Joseph Lubin. However, since its inception Vitalik has been the posterboy for Ethereum as well as an outspoken member of the crypto community.
ETH is also still one of the few chains that you can mine with a CPU/GPU, however, results will vary depending on hardware. Unlike Bitcoin, which will only ever have 21 million coins in supply, ETH has no hard cap. This means, if we take block difficulty out of the equation, mining can happen indefinitely.
There is no end to what ETH is capable of financially or as a decentralized web OS which is why I believe it will stay top 5 (prob #2) for the foreseeable future.