Testing how well a system performs under expected user load. Like seeing how many people can fit in an elevator before it becomes uncomfortable.
Before Black Friday, e-commerce sites do load testing to ensure their websites can handle millions of shoppers.
Load testing is a practice, not a single cloud service. Azure provides a first-party managed load testing product. On AWS, a common equivalent is the AWS Distributed Load Testing solution (a reference implementation) plus CloudWatch for metrics; teams also use third-party tools on AWS. GCP and OCI typically rely on third-party tools (e.g., JMeter, k6, Locust) running on compute/serverless, combined with native monitoring for results.