What is meant by "on the Internet"?

Many sources of information are available on the Internet. Some are free and some are fee-based. Often, when people hear that information is "on the Internet", they assume that it is freely available to anyone. This is not always true.

If you are an employee of Massachusetts General Hospital, you have access to a great many electronic resources through Treadwell Library. If you have a public library card you also have access to a range of databases at no charge. These are all available to you over the Internet. But they are not free resources. What type of information is freely available?