Ethereum is the second largest cryptocurrency in the world behind Bitcoin. It's been actually growing a lot faster than Bitcoin. BTC has grown around 300% this year but ETH is up about 4000%.
And then what's really interesting is: not only is it growing quickly, but if you visit other exchanges, it's becoming much more used.
What's happening is BTC is being used as a way to store value but because of the transaction costs and the slow network time, trading ETH is actually winning out and they dominate the list mainly because it is being used a lot more for transactions and it got a lot of advantages with the better block time and the better technology.
So it's being used in favor of those and then once people have the transaction done, they'll convert it in a Bitcoin and store the value there.
Bitcoin is Awesome! But… It is only has one function: currency. Proof of Work is very wasteful energy-wise. What if you wanted to do more with “Blockchain Technology? ENTER ETHEREUM …
The short answer is that Ethereum is an application platform.
Ethereum is an application platform for "Not just money! Asset issuance, crowdfunding, domain registration, title registration, gambling, prediction markets, internet of things, voting, hundreds of applications!"