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That's because it is owned by Google. lol
TL;DR: they don't. Each company providing the browser has different ways of generating income. The browser doesn't make money, the company does. But the browser can be a tool to make money. Take the following companies and their browsers for example: Google - Chrome, Microsoft - ME/IE, Mozilla - Firefox. 1. This is a concept in economics/marketing called "market penetration". The more users a product has, the more reputation, trust, ... it gains from it's users. As time goes on, the company has more influence and the users become more dependent on the product. Well-maintained relationships are considered a profit in business sense. People give reviews and share their opinion, which brings in even more users - a good foundation for the company to launch upcoming products. Browsers are deeply integrated with and related to their company's services. Chrome is free, and it links to many other Google apps, which may not be free. 2. Search Royalties. A company will pay the browser's owner so that their search engine always stays the default search engine. Why would they do that? See (1). 3. Another marketing/pricing strategy, though a bit deprecated. Imagine a product of $4 with a shipping fee of $1 and the same product, free shipping, for $5. People like free things, they always buy the 2nd. In the old days, not every Internet user can install a browser on their own. It's "nice" of Microsoft to always have IE/ME to come along with the OS. In reality, the price is already included in the OS license. 4. Donation. Mostly for open source browsers (e.g Firefox, Linux browsers). P/S: Ad is still the main source of income, especially with Google. Their users data and filtering algorithms are enough to triple the price for advertising agencies.