Ethereum is a decentralized, open-source blockchain platform introduced in 2015. It enables developers to build peer-to-peer applications, referred to as decentralized applications or dApps. These dApps run on top of the Ethereum blockchain, offering a range of functionalities to users, from smart contracts to token issuance. 

 

One of the key features of Ethereum is its ability to execute smart contracts automatically. These are self-executing contracts that contain the terms of the agreement between parties and are enforced by the Ethereum blockchain. This feature eliminates the need for intermediaries like banks or lawyers, making transactions faster, cheaper, and more secure. 

 

Ethereum also introduced its own cryptocurrency, Ether (ETH), which is used to incentivize miners to secure the network and to pay transaction fees. Ether is now widely used for a variety of purposes, such as making payments, storing value, and token issuance. 

 

In conclusion, Ethereum has become a crucial element of the blockchain ecosystem, enabling developers to build decentralized applications and execute smart contracts. Its wide range of use cases and functionalities have made it a popular platform among developers, investors and users.