Amazon Web Services (AWS) is the Cloud Computing platform by Amazon born in 2006. It's an uberly complex infrastructure with geographically distributed nodes all over the world in order to guarantee the best reliability.
AWS offers a plenty of paid Cloud services, for instance S3 for storage, EC2 for computing and RDS for databases. You can access to the platform by registering at https://aws.amazon.com/ and take advantage of the free (and limited) plan and use Amazon's Cloud resources.