If you have a good, commercial connection to the Internet or if the site(s) or service(s) that you want to provide are targeted to people who don't mind using a special address to get to them then you might be a candidate to host your own Internet server. For the sake of simplicity we will focus on web hosting, but most of this also applies to FTP and other online protocols.
OK, so like we said you have a good strong connection to the Internet. If this connection is in you home then odds are good that your Internet Serviece Provider (ISP) will block the default port that web sites use to allow web browsers to connect. I know people that host family web sites this way, but this means that anyone who connects must know the alternate port and be savvy enough to put it into the web browser address to get there.
If you pass all these obstacles now you have to confront the issue of whether you want the headache. If you don't maintain servers for a living or really, really like it then you want to think twice about this route. Hosting is now quite inexpensive and if arranged correctly (with our help we hope) is much less costly in all senses of the term.