Getting on the Internet requires:
Computer and Monitor
Telephone Line
Internet Service Provider (ISP)
Communications Software

An Internet Service Provider (ISP) is a company that provides you with access to the Internet. When your modem makes a local phone call to connect to the Internet, it actually dials your Internet Service Provider, which, after verifying that you have an active account, manages your connection to the Internet.

America Online (AOL) and CompuServe (AOL has purchased CompuServe) are national online services which provide access to the Internet and their own content services to subscribers. National ISPs, like Interport or Netcom, and local and regional ISPs usually just give you access to the Internet. Pricing for all these services is usually a flat monthly charge (about $20/month) for unlimited use. This includes an e-mail address and, typically, space on the ISP's server where you can store your personal Web pages.

National Online Services & Internet Service Providers
America Online
Lists of Provider Lists
Rather than maintaining a single list of all Internet Providers, this site provides HTML links to other lists of providers. Many of these lists are limited to a fixed geographic region.
MCI WorldCom

Internet Primer
Thirteen Ed Online