Litecoin is a digital currency designed to facilitate peer-to-peer payments with low or non-existent fees. It was created in October of 2011 by Charlie Lee (link?), a former employee of Coinbase. It is one of the four coins you can buy on Coinbase, currently.
Litecoin was originally a digital currency fork from the Bitcoin blockchain and is being built mainly as a medium of exchange (rather than a store of value). Unlike the Bitcoin Cash fork that has been contentions, the Litecoin fork has been friendly, often testing and implementing new software and upgrades that may end up being part of Bitcoin.
*Disclaimer: Charlie Lee has recently been scrutinized for selling his entire share of Litecoin. He claims that he did not want his financial gain from the coin to interfere with the technology he is trying to build and promote. As of early 2018, the timing of his sale coincide with the all time high (ATH) in the Litecoin market. He is being accused of selling at the top, but time will tell if 2018 brings higher Litecoin prices.