Because the Internet is less stable than paper sources in a library, most instructors advise against using it for all of your sources. But researching using the Internet does have some advantages. It's topical, it's useful when you're after a specific piece of information, and it's easy to download, print, and edit files. But also be aware of the disadvantages of the Internet as a research tool.
Information is disorganized and sometimes unreliable.
Be especially careful about using information from a personal homepage. Often paper sources are cited for statistics you find on the Internet. You might consider finding the paper source rather than citing the Internet source, since the paper source is more stable. Often the bibliographies of your paper sources will lead you to websites. Websites that are cited by books and articles about your topic are often perceived as a more reliable source of information.