In the hosting world, overselling means advertising attributes which a client buys, but can’t really take advantage of. Many of the attributes of a given website hosting solution can fall under this category - hard disk space, monthly traffic, database storage space, and many others. A plan may come with unrestricted disk space, for instance, but the majority of hosting service providers make accounts on just a single server which can have only so many hard drives and considering the fact that all customers upload content, there won't be any space left on the server at some point or there will be some secret quotas in order to make sure that every single client has their share, although everyone has paid for unlimited space. Since most web hosting Control Panels are meant to work on one server, many companies don't have any choice but to oversell, which is nothing else but deceiving their customers.