As you can see on the review page of the product, Skype Toolbar is a browser utility developed by Skype Limited. It comes packaged with Skype installer and you can choose to install it when you run the full installation package. It is fully compatible with the latest versions of Internet Explorer, Firefox and Google Chrome and it automatically highlight every phone number found on a web page. When you click a phone number from a specific website, you can dial it directly through Skype or add it to your contacts list. If you don't need the utility, you can uninstall it following the steps below:
Google Chrome and other Chromium-based browsers: type chrome://extensions in the address bar. Press the trash can icon next to the Skype Toolbar.
Firefox: press Shift+Ctrl+A (or open Tools → Add-ons). Press Disable next to the Skype Toolbar. If you can't find the toolbar in the Extensions tab, switch to the Plugins tab and look there.
Opera 12.x and older: press Ctrl+Shift+E (or press the Opera button → Extensions → Manage extensions) to open the Extensions menu. Press Uninstall next to the Skype Toolbar.
Internet Explorer: open Tools → Manage Add-ons. Select the Skype Toolbar and press Disable.