Before you can understand ethereum, it helps to first understand the internet.
Today, our personal data, passwords and financial information are all largely stored on other people's computers - in clouds and servers owned by companies like Amazon, Facebook or Google. Even this CoinDesk article is stored on a server controlled by a company that charges to hold this data should it be called upon.
This setup has a number of conveniences, as these companies deploy teams of specialists to help store and secure this data, and remove the costs that come with hosting and uptime.
But with this convenience, there is also vulnerability. As we've learned, a hacker or a government can gain unwelcome access to your files without your knowledge, by influencing or attacking a third-party service - meaning they can steal, leak or change important information.
Brian Behlendorf, creator of the Apache Web Server, has gone so far as to label this centralized design the "original sin" of the Internet. Some like Behlendorf argue the Internet was always meant to be decentralized, and a splintered movement has sprung up around using new tools, including blockchain technology, to help achieve this goal.
Ethereum is one of the newest technologies to join this movement.
While bitcoin aims to disrupt PayPal and online banking, ethereum has the goal of using a blockchain to replace internet third parties -- those that store data, transfer mortgages and keep track of complex financial instruments.