Ethereum is a global computer capable of running decentralized applications, providing a different set of possibilities, especially for the development of them: a time of rapid development, security and the ability for different applications to interact very efficiently.
This allows to create tokens, markets, store records of debts or promises, move funds according to instructions given in the past (such as a will or a futures contract) and many other things that have not yet been invented, all without intermediaries or risk of a counterpart.
In general, there are three types of applications that can be implemented on Ethereum. The first category is financial applications, which provide users with more powerful ways to manage and manage contracts using their money. This includes sub-monies, financial derivatives, hedge contracts, savings portfolios, testaments, and ultimately, even some types of employment contracts. The second category are applications that are not completely financial where money is involved but there is a non-monetary side of weight; a perfect example of this are the rewards for solving computer problems. Finally, there are applications such as online voting and decentralized government that are not financial applications at all.
The blockchain of Ethereum is very similar to that of bitcoin, but its programming language allows developers to create intelligent contracts which serve to manage transactions and automate certain results. If a traditional contract describes the terms of a relationship, a smart contract ensures that those terms are met. They are programs that execute the contract automatically once the predefined conditions are met, eliminating unnecessary delays and the cost of executing it manually.
Source: Ethereum Whitepaper