Hi duhsang What a question!! To use Mozilla Firefox effectively, you can follow these official guidelines and features provided by Mozilla Support and the Mozilla Blog. [[Get started with Firefox - An overview of the main features]] Firefox is built with privacy as a priority. You can use several tools to protect your data. Private Browsing, Enhanced Tracking Protection, Password Manager. [https://www.firefox.com/en-US/user-privacy/| How Firefox Protects Your Data] One of Firefox's best features is how much you can change it to fit your needs. Picture-in-Picture: You can "pop out" a video from a webpage so it stays on top while you work in other tabs or apps. Look for the blue icon on the right side of videos. Reader View: For a clutter-free reading experience, click the document icon in the address bar on supported articles to remove ads and distractions. Web Apps (Windows only): In recent versions, you can install websites as standalone web apps that appear in your Windows taskbar. [[Use web apps in Firefox for Windows]] For more detailed guides on specific settings, you can visit the [https://support.mozilla.org/en-US/products/firefox| Firefox Help homepage] [[Access Mozilla services with a Mozilla account]]