What is a utility token?

Utility tokens provide you with the rights to access, support and use decentralized network.

e.g. on the Ethereum blockchain, the native token ‘ether’ (ETH) allows you to execute transactions on the network (by paying gas fees), incentivizes you to validate transactions on the network (mining rewards) and pay to access services built on the network. 

A token can best be thought of as a digital representation of a metered resource within a decentralized network.