Serverless computing

Unlike containers or virtual machines, serverless computing offers users a pay-as-you-go cost structure. Customers of a serverless computing cloud service only pay when the function required is executed in the cloud. The following diagram illustrates a serverless computing system:

Although it is called serverless, physical servers are indeed used. However, customers need not worry about the underlying hardware and resources. 

Serverless computing works well for functions that are stateless and event driven.