• Kaution means the security deposit you need to pay with the first rent (usually around 2-3 monthly rents). The deposit will be payed back to you when moving out, provided you caused no damage to the apartment.
• +NK=Nebenkosten are the utilities fees (monthly cost for heating, TV,  or electricity, stairwell cleaning, janitor, etc.), which are not included in the rent and will be charged extra.
• Provision: If the apartment is procured by a realtor you will probably need to pay a commission (approx. two monthly rents). Therefore, it is worthwhile to look for apartments offered directly by the landlord (Vermieter) –these flats are often advertised as provisionsfrei=no commission charged.
• Electricity (Strom) is normally not included in the rent. You will need to get a contract with an electricity company. It is usually possible to simply resume the contract of the preceding tenant.
• If the indicated monthly rent is specified as “warm”, the monthly payment includes the costs for heating. The specification “kalt” means the rent without heating costs, which will be charged extra.
• WG is short for “Wohngemeinschaft” and means shared flat.
• Zwischenmiete means a room/apartment offer for a limited period of time (usually during a temporary absence of the regular tenant/flatmate).

Abbreviations frequently used in accommodation adverts: