Mozilla's Firefox is a highly-used Web browser that you can use on your Mac or Windows operating system to take advantage of the enhanced security that the browser provides. With Firefox, you can keep websites from loading in your browser window by installing an "add-on," which is a small application that works with Firefox to perform a specific task. Using the Firefox toolbar, you can install your own add-on to block URLs in your browser in just a few clicks.

Launch your Firefox Web browser, select "Add-ons" from the "Tools" menu and click the "Get Add-ons" tab.
Type in a term like "block URLs" or "block websites" in the search box and click the search button to get a listing of all the relevant extensions, such as BlockSite and SimpleBlock, that perform this task.
Read through the description of each add-on to determine the one that works best for you and click the "Add to Firefox" button next to your choice.
Click the "Install Now" button and then click the "Restart Firefox" button to make sure the add-on is installed on your browser. When Firefox starts again, highlight your add-on and click the "Install" button again.
Click the "Options" button and follow the prompts to enter the URL addresses that you want to block.

Cyber Security