Ethereum was created to solve some of the shortcomings of Bitcoin. Under Bitcoin, you can send and receive transactions and perform other vital functions however smart contracts aren't supported but Ethereum solves that problem. It allows Developers to build whatever interactive performances they want in their smart contracts. Since Ethereum is decentralized, anyone can build and launch anything hence it's popularity. It offers a high level of customization that allows Developers to create products like: Decentralized application, Complex Smart Contracts, Tokens, e.t.c
The Ethereum coin that powers the network is officially known as Ether and widely known by it's ticker symbol - ETH. The best way to think of ETH is that it's the currency you use to pay for the execution of a smart contract.
Ether has the potential to surpass Bitcoin and become the leading Crypto currency since It can never have an inflation rate of 0% unlike Bitcoin.