Performance Engineering is the practice of ensuring that a system, application, or product operates efficiently and effectively under various conditions. It involves analyzing and optimizing performance metrics such as speed, responsiveness, and resource usage. By focusing on these aspects, engineers can identify potential bottlenecks and improve the overall user experience. This discipline often includes activities like load testing, stress testing, and capacity planning. Tools and techniques are used to simulate real-world scenarios, helping teams like software developers and system architects to make informed decisions. Ultimately, the goal is to deliver high-quality products that meet user expectations and business requirements.