Free Web Hosting
This is generally a shared hosting solution (meaning many websites share the same computer resources.) These are generally companies offering web space in return for placing their advertiser's banners on your content. The web address you get with a free hosting provider may take the form of a "subdomain" which means prefixing a name of your choice onto the front of a domain name that the provider has registered with a registrar for their own uses. For example: yoursite.domain.com, yourpage.someplace.net.
Gotcha: It appears search engines have trouble differentiating subdomains from the parent domain. If you happen to create your page on a domain that has been flagged as a bad content provider, you will be penalized as a result. This may not mean much to you until you are invested--so be warned (this has happened to me.) It's often preferable to register your own domain rather than using a subdomain--however, this almost always means you have to pay.
Free hosting services sometimes offer upgrades such as turning off banners, more web space, FTP in addition to a web-based file manager, CGI scripting access with Perl, PHP, or other web languages, and some additional tools and features. In my experience the upgraded services may not be in parity with other pay-only web hosting providers so if you are considering paying for hosting, then you may want to avoid the free hosting scene altogether and instead focus on evaluating paid provider offers.
This is a category that has thrived in the past when advertising dynamics were different than they are today. That said, there are still a few hosts around offering free services. We don't recommend free hosting--but if you are determined to pay nothing here you go.
General Free Hosting Providers