You can also host your website on WordPress.com, but that's different from the kind of hosting mentioned above. WordPress.com uses the same code from WordPress.org, but it hides the server code and handles the hosting for you. In that sense, it resembles entries in our online site builder roundup. It's a simpler but less flexible and customizable way to approach WordPress hosting. It's definitely easier, but if you want to tinker and adjust and optimize every aspect of your site, it might not be for you.
Many services offer so-called unlimited or unmetered service for whatever amount of bandwidth, disk storage and sites you use. It's important to understand that most terms of service actually do limit the definition of "unlimited" to what's considered reasonable use. The bottom line is simple: if you're building a pretty basic website, unlimited means you don't need to worry. But if you're trying to do something excessive (or illegal, immoral or fattening), the fine print in the terms of service will trigger, and you'll either be asked to spend more or go elsewhere.