If you use on-premises servers or EC2 instances, you are likely not using 100% of the compute capacity at all times. Many customers only use 10–20% of the available capacity in their EC2 fleet at any point in time. This average is also affected by high availability and Disaster Recovery requirements, which typically result in idle servers waiting for traffic from failovers. In the on-demand AWS Lambda compute model, you pay per request and by duration of time. Additionally, serverless architectures can lower the overall Total Cost of Ownership (TCO) since many of the networking, security, and DevOps management tasks are included in the cost of the service.