AWS is a product by Amazon and stands for "Amazon Web Services". These web services they provide are hosted in the Amazon cloud.
At our company we prefer hosting our applications in the Amazon cloud.
This chapter of the knowledge base provides some basic instructions on how to set up some of the services that are available through AWS. Of course we cannot cover everything there is to know about the services that we use, but Amazon provides a very extensive knowledge base as well, be sure to check: