Let's call things like they are in the Lightspeed Media lawsuits. People are using web browsers to access pornography through a website.
They generally get to these websites by using "porn password" webpages when looking for free pornography online. Sometimes these passwords are included in a URL, for example http://user:password@URL.com/
Generally, the people who run these websites make their money off of advertising, and obtain their passwords from a wide variety of common hacking methods.