How do browsers make money?

As stated, how does Microsoft make money off of IE, or Mozilla make money from Firefox, seeing as they're given away for free?

Porn subsidies.

Microsoft doesn't need to make money off IE. Firefox? That's a good question. Don't know.

MS makes money from the development tools they sell to create content.

But IE isn't really free, it's integrated in the windows OS. Whether you're browsing "my computer" or porn on the internet it's pretty much the same software formatting the display.

Getting more users on IE ensures a demand for development tools that are likely to play well with IE.

Firefox on the other hand is the product of some sort of quasi communist organization (they have their own "manifesto"). Volunteers provide the development effort. Their products are given away; duplicating them for redistribution is encouraged. Their core, the Mozilla Foundation is donor supported. It wouldn't surprise me if MS is one of the major contributors. Certainly other corporations are. They don't want to see MS dominate the channel that is used for most of today's media.

Fascinating.

OmniGroup still actually sells OmniWeb. If you like what it does uniquely, it's totally worth it.