With a shared hosting plan, you are renting space on a server that you share with other website owners. This also means you're sharing resources like bandwidth, memory, and processing power. This can be a problem, because a web host company typically supports hundreds, even thousands, of websites on a single server. Most of these websites will get very little traffic, allowing those who do see higher levels of traffic to use the resources they need. Nevertheless, there are no guarantees that you will get the resources necessary to support your website.
One's website is placed on the same server as many other sites, ranging from a few sites to hundreds of websites. Typically, all domains may share a common pool of server resources, such as RAM and the CPU. The features available with this type of service can be quite basic and not flexible in terms of software and updates. Resellers often sell shared web hosting and web companies often have reseller accounts to provide hosting for clients.
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.