In this guide, we will dive into the world of Gatling, the potent open-source tool for web application load-testing. Starting with Gatling installation, uncover the power of Gatling Recorder, perfect for capturing user journeys and transforming them into scripts effortlessly. We will start by executing our first Gatling script and gain insights from the application through testing. This will be followed by core topics such as checking response codes, examining response bodies, and data extraction; we will then master debugging session variables and code reuse techniques. Moving ahead, we will dive into advanced topics such as looping HTTP calls, authentication and working with CSV feeders. We will understand basic and complex custom feeders, as well as templating files. We will introduce load simulations, ramping up users, and running Gatling from the command line with runtime parameters. Throughout the course, we will tackle challenges, and learn to monitor test executions with Gatling test result reports. We will also guide you on integrating Gatling into CI pipelines, covering GitHub repositories, and Travis CI configuration. By the end, you will be a Gatling expert, capable of effectively load-testing web applications and seamlessly integrating Gatling into CI/CD workflows, ensuring optimal performance and reliability.