DreamHost Hosting Plans
You may get dedicated or shared hosting. With shared hosting, you share a server with other people. With dedicated hosting, you get a whole server to yourself. For many sites, shared hosting is adequate until your site becomes very popular, or you need extra server processing power.
DreamHost's shared hosting plans are described in detail at http://www.dreamhost.com/shared/comparison.html
Dedicated server plans can be found at http://www.dreamhost.com/dedicated/
(DreamHost once offered DreamHost Apps plan, but that has been discontinued and all its users should have migrated to one of the other hosting plans).