Gmail add-ons are tools that extend the functionality of your inbox, making it easier to get work done. They can be found directly in Gmail and installed by clicking the "Get Add-ons" icon. To install, click on the app you want, then click "Install", giving permission as needed. There are 10 best add-ons for different purposes such as cloud file sharing, project management, scheduling virtual meetings, to-do list management, and more. Some popular add-ons include Dropbox for Gmail, Trello for Gmail, Asana for Gmail, Zoom for Gmail, Todoist for Gmail, Inbox When Ready for Gmail, Checker Plus for Gmail, Sortd for Gmail, and Zapier. These tools can be accessed in both the web version of Gmail and the mobile app. To remove an add-on, click on "Get Add-ons" then search for the add-on to uninstall.