The Tor Browser is a technology that prevents third parties (be they companies, advertisers, law enforcement etc) knowing your location and tracking your Internet habits. In general terms, when a person connects to the Internet one’s Internet Service Provider (ISP) assigns you an IP address. Websites one visits know one’s IP address (and your ISP). This means that almost everything you do online is identifiable.
The Tor Browser uses technology to bounce your communication around a network so that nobody can know for sure what sites you visit and the sites, themselves, do not know that it is you who is visiting.
The original technology behind the Tor Browser was first developed for the US Navy, and received the vast amount of its funding from the US Department of Defense. Initially created to prevent corporate snooping, Tor has since become a means of stopping government snooping.