I rent an apartment in apartment complex
Do you need to go through a background check to get an apartment?
in North America (although in some cities "flat" is used for a unit which is part of a house containing two or three units, typically one to a floor). In the UK, the term apartment is more usual in professional real estate and architectural circles where otherwise the term "flat" is used commonly, but not exclusively, for an apartment on a single level (hence a 'flat' apartment).
In some countries the word "unit" is a more general term referring to both
Plottage
Plottage is the increase in value realized by combining adjacent parcels of land into one larger parcel. The process of combining the parcels is known as assemblage. Generally, the value of the whole parcel will be greater than the sum of the individual smaller parcels.
The Federal Trade Commission states the following: 
When you apply to rent an apartment or house, you will need:
- information about your employer and your income
- identification, like a driver’s license, for a credit or background check