AOL slept with Microsoft and many other big companies to get its service promoted. AOL made IE the defailt AOL browser to get that AOL install software on the Windows 9X installs so people can more easily get on their service. Just one click away from installing it, and then signing up for an AOL account.
Once AOL got big and powerful from sleeping with Microsoft, they used that extra money to buy out Netscape, and merge with Time/Warner/Turner. Not to mention the buyout of Compuserve, their greatest rival.
Remember when AOL was a small company, and didn't have a big interface program bigger than 1M in an install disk? Remember when the AOL Windows client fit on a 720K MS-DOS or 800K MacOS disk for the Mac client?