Microsoft succeeded in having ISPs and PC vendors distribute Internet Explorer to their customers instead of Netscape Navigator, mostly due to Microsoft using its leverage from Windows OEM licenses, and partly aided by Microsoft's investment in making IE brandable, such that a customized version of IE could be offered. Also, web developers used proprietary, browser-specific extensions in web pages. Both Microsoft and Netscape did this, having added many proprietary HTML tags to their browsers, which forced users to choose between two competing and almost incompatible web browsers.