Subletting is renting a place that you rent out in parts. Example is you rent an apartment with 2 bedrooms and then you sublet 1 bedroom to another tenant. Some tenants are doing that commonly in a house that they rent but usually with the permission of the landlord. When we rented a big house with 3 bedrooms, the landlord even encouraged us to sublet 1 or 2 rooms because there were only the 2 of us then (my husband and I). But since we want privacy so we just shouldered the expensive rent and had the house all for us.