There's no technical reason why not. Any computer with an internet
connection can be used as a web server, provided it has the appropriate
software installed. However, unless you have a reason for hosting on your
own, you'll probably find it much easier to upload the pages you want to
make available to a free or low cost hosting service. Many ISP's offer free
hosting as part of a paid subscription.
If you want external users to see your Web site, then there are
several possible reasons why it might be difficult.
1. Unless you have a business class agreement with your ISP, hosting
any kind of server may be prohibited.
2. If you have a dynamic IP address, it will be more difficult for
others to find you. You will have to use one of the dynamic DNS
services.
3. If you have a firewall, you will have to configure it to pass
requests through to the computer that hosts the Web site.