JMeter, developed by Apache Software Foundation, is an open-source Java application for performance and load testing. It's widely used to test the performance of web applications, APIs, and databases, simulating heavy loads to analyze performance under different scenarios. With its user-friendly interface and extensive features, JMeter allows testers to accurately measure response times, throughput, and server performance. Those interested in mastering JMeter can explore comprehensive JMeter Training in Chennai offered by FITA Academy for in-depth understanding and practical skills.