Performance Testing is a type of software testing that evaluates how a system behaves under various conditions. It helps ensure that applications can handle expected user loads, respond quickly, and remain stable during peak usage. By simulating multiple users and measuring response times, performance testing identifies bottlenecks and areas for improvement, ensuring a smooth user experience. This testing is crucial for applications like websites, mobile apps, and enterprise software, where performance can significantly impact user satisfaction. Tools like JMeter and LoadRunner are commonly used to conduct these tests, providing valuable insights that help developers optimize their systems before launch.