Tenancy at will: When there is no specified time for the lease it is considered to be an at will tenancy which means that the lease can be terminated by ten days notice from either the landlord or the tenant.
Periodic Tenancy: A tenancy which runs for a certain period of time, renewable for the same period of time (ex. one year to the ext).
Lodger: one who has the use of property without actual or exclusive possession, such as one who lives in spare room of a house whose owner retains direct control , supervision or care of entire house.