In this Selenium Java tutorial, we explored three different ways to handle modifications on HTTP request headers in a Java-Selenium project. We started by understanding what HTTP headers are and their importance in the HTTP protocol. We then delved into scenarios where modifying HTTP request headers is necessary, such as testing guest mode or changing authentication headers. To achieve this, we considered using REST Assured library, browser mob-proxy, or Firefox extension to modify the header requests. With the REST Assured approach, we used a Java class named RequestHeaderChangeDemo to create a mechanism for customizing request headers. We also explored how to use browser mob-proxy and Firefox extension to modify HTTP request headers in our test automation script. Ultimately, we concluded that while each method has its own advantages, using REST Assured library is the most recommended approach due to its flexibility and maintainability.