Litecoin was created in 2011 by a former Google engineer Charles Lee. Litecoin was intended to be an improvement upon Bitcoin, with some major changes to bitcoins parameters being the main differentiating factor.
Litecoin uses the same peer-to-peer blockchain technology as Bitcoin, but runs at a much higher block frequency. Where in Bitcoin a new block is created roughly every 10 minutes, in Litecoin blocks are created every 2.5 minutes on average. As such, the maximum amount of Litecoins that can be created is 4 times Bitcoins 21 million, at 84 million.
But, Litecoin is more than just taking Bitcoin and multiplying and dividing some values by 4 - Litecoin uses a different hashing algorithm, called Scrypt. Scrypt is a memory-limited algorithm, which means it is not as easy to create dedicated ASICS for mining as it was for Bitcoin. As such, Litecoin mining can't use the same dedicated hardware produced for Bitcoin mining.