After the foreclosure sale, when a new deed has been recorded with a new owner’s name on it, you go from homeowner to tenant. A commonly held belief is that you aren’t legally a tenant unless you have entered into a formal landlord–tenant relationship and agreed to pay rent. In fact, with a couple of exceptions, you are considered a tenant (typically termed a tenant at will or tenant by sufferance). You are entitled to remain in your home until you are evicted using the same court procedures that apply to other tenants—except that you may not get as much notice that you must leave.
The first step toward eviction is to send you a written notice stating that you must move out. (See your state’s page in the appendix for the rules on what kind of notice you are entitled to in your state.) How soon you are likely to get such a notice depends on who owns your house after the foreclosure sale: a new buyer or the lender.