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These browsers allow you to install extensions that increase their functionality. There are extensions for both that allow you to block yourself from specific sites during certain hours of the day. Both Firefox and Chrome are free to download. There are several plugins available that will allow you to block sites such as Facebook that keep you from your work. One of the most popular extensions for Firefox is LeechBlock, while Chrome's most popular extension is StayFocused.   Install LeechBlock on FireFox. Click the Firefox button and select Add-ons. Enter leechblock into the "Search all add-ons" field. Click the Install button to the right of the LeechBlock entry of the search results. LeechBlock will be automatically downloaded and installed. Restart Firefox.  Install StayFocused on Chrome. Click the Chrome menu button. Select Tools → Extensions. Scroll to the bottom of the list and click the "Get more extensions" link. Enter stayfocused into the "Search the store" field. Click the "+Free" button next to StayFocused at the top of the Extensions results. Click the "Add" button in the confirmation box that appears.  Install Nanny on Chrome. Visit the Chrome Web Store.  Nanny for Google Chrome can block sites, such as Facebook, on your Chrome. Use the search field on the top left corner of the page to search for it. From the search results, click on Nanny for Google Chrome to see more details about it. Click the “Add to Chrome” button on the top right corner of the page. A confirmation message will appear informing you of what the new extension will do. Click on the “Add” button. Once you've installed your extension, you will need to configure it to block Facebook and set the times that you want it blocked. The process is a little different in each extension.   LeechBlock - Click the Firefox menu and select Add-ons. Find LeechBlock on the list and click the Options button. Add "www.facebook.com" to the large text field in the middle of the Options window.  Click the "When to block" tab and set your block schedule. All times are entered in 24-hour format. You can set sites to be blocked after a certain amount of time on them or during specific times of the day, or both. Click the "How to block" tab to select what happens when you visit a blocked site. By default, it will go to a LeechBlock notification, but you can set it to redirect to any site that you wish. Click the Advanced tab to set your advanced options. These include disabling the LeechBlock options menu during your blocked hours and blocking access to Firefox configuration menus. Only select these if you understand the consequences of doing so (you will not be able to get to these menus, even if you need them for other programs, during the block time). Add a password. Click the Access Control tab at the top of the Options window to add a password to LeechBlock. This password is not for security, but to add an extra roadblock between you and disabling the block. This will give you extra time to consider disabling the block and being unproductive.    StayFocused. Click the StayFocused icon in your browser toolbar. It should have appeared immediately after installing the extension. Click the "Settings" link at the bottom of the box that appears.  Click the "Blocked Sites" menu option. You can find it in the menu on the left side of the Settings page. Add "www.facebook.com" to the field and click the "Add Blocked Sites" button. If you want to keep yourself from disabling StayFocused, click the "Block the Chrome Extensions page!" to add the Extensions page to your blocked list. Set your blocking schedule. Use the top four menu options to set your blocking schedule. "Max Time Allowed" lets you enable a timer for all of your blocked sites. Once you reach this time limit, you can no longer access the blocked sites for the day. "Active Days" lets you set what days StayFocused enforces the block. "Active Hours" sets the time of day that the sites are blocked for. "Daily Reset Time" is the time of day that your time limit resets. Adjust the Nuclear Option. This is the last-resort button for increasing your productivity. By default it will block ALL sites for the specified time, but you can change it to just block the sites on your list. Add a challenge. If you feel like you'll be tempted to disable the block, you can add a challenge to get back into the settings. You will be required to type a specific paragraph without making any typos or backspaces.    Nanny.  Click the button with three horizontal lines at the upper right corner of your Google Chrome browser. This will bring out a submenu. Look for “Settings” and click on it.  From the Settings page, click the Extensions link from the left panel menu. The Extensions page will load, listing all the extensions installed on your Google Chrome browser. You can see Nanny for Google Chrome here.  Open the settings for Nanny for Google Chrome. Click the Options link under Nanny for Google Chrome. This will open another window or tab for Nanny for Google Chrome’s settings. Block Facebook for a certain period. Click the “Blocked URLs” tab on the settings page. This is where you can configure what and when to block sites like Facebook. Type in the name of the block set, like “Facebook block,” in the Block Set field. Type in “facebook.com” in the URLs field. You can also type in other sites you want to block with Facebook. Key in the start and end times when Facebook will be blocked in the Blocked Time field. The format should be in military time, e.g., 0900-1700,1900-2100 for 9AM-5PM and 7PM-9PM, respectively. It can accept multiple time slots separated by a comma. Tick the checkboxes for the days when the block will be active. If you want to only block Facebook on weekdays, you should tick Monday, Tuesday, Wednesday, Thursday, and Friday only. Save. When you’re done configuring when to block Facebook, click the “Save URL” button at the bottom for the form. Nanny for Google Chrome will be activated when the set times come, and you won’t be able to access Facebook anymore during those times. Once your schedule and Facebook block is set, your extension is active. In order to disable it, you will need to go through whatever steps you put in place to keep yourself from doing so. Try to resist! Install extensions on all of your installed browsers to keep you from switching between them to circumnavigate the block.

Summary:
Download Firefox or Chrome. Download a productivity extension. Configure your extension. Use the extension.