Golem is a global, open sourced, decentralized supercomputer that anyone can access. It's made up of the combined power of user's machines, from personal laptops to entire datacenters.
Anyone will be able to use Golem to compute (almost) any program you can think of, from rendering to research to running websites, in a completely decentralized & inexpensive way.
The Golem Network is a decentralized sharing economy of computing power, where anyone can make money 'renting' out their computing power or developing & selling software. Built on the Ethereum blockchain, the Golem token is by far the largest in terms of market capitalization and activity. Take a look at: https://golem.network/alpha.html