Ether (ETH) is the native digital currency of Ethereum. Developers are required to pay ETH for application developments.
The concept of Ethereum is developed by program designer, Vitalik Buterin. It is initiated through an ICO in 2014.
The most important aspect of Ethereum is the smart contract applications. Ethereum is a blockchain technology equipped with smart contract functionalities. It supports various derived applications. A number of smart contract applications are currently built on Ethereum.
The source code of Ethereum is open-source, similar to Google's Android. It provides the framework with public source code available to the application developers, and further maintains the framework development collectively.
Due to the fact that these applications operate on blockchain, they are equipped with the eternity of blockchain. Beyond that, these applications get to control digital currencies. For example, they can store and transfer digital currencies. Furthermore, blockchain guarantees the execution of the scripted content as no single entity is able to intervene its operations.
The most promising application remains to be the following, which is applying smart contracts on stocks, bonds and other financial derivatives. Smart contracts automate many aspects of financial markets, and simplify program-intensive transactions related to various financial instruments and service systems.
Financial instrument is simply one of the many applications of smart contracts. As the technology matures, other assets will be able to be transacted and stored on blockchain.