What is Load Testing

Definition

Load testing is a type of performance testing that subjects a system to expected and peak levels of concurrent demand to verify it remains stable, responsive, and within performance targets under realistic workloads.

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Confirms the system stays stable and responsive under expected peak demand
Reveals how performance degrades as concurrent load increases
Validates capacity assumptions ahead of high-traffic events
Reduces outage risk by exposing breaking points before users do

Real World Example

Ahead of a flash sale, an e-commerce team load-tests the checkout flow at projected peak traffic, confirming it holds up and revealing the exact concurrency level at which response times start to climb.

FAQs

What does load testing verify?

It verifies that a system stays stable and meets performance targets under expected and peak concurrent demand.

How does load testing differ from stress testing?

Load testing checks behaviour under expected peak load, while stress testing pushes beyond limits to find the breaking point.

When should load testing be done?

Before high-traffic events or releases, to confirm capacity and uncover degradation points before real users do.