Please explain: rents in Germany / Berlin

Cold rent means that you pay basic rent for the residence and there are no extra costs included in your monthly payment.
Warm rent means that your monthly payment includes the basic rent for the residence and additional costs - called Umlagen or Nebenkosten. Nebenkosten can include heating, water, wastewater disposal, trash and recycling pick-up, furnace inspection and other expenses. It is important to make sure you know exactly what is included in the Nebenkosten and how the costs are for the various items are calculated before signing a lease.

Many of the services and utilities included in the Nebenkosten can generally be considered "communal" services. In other words, the suppliers provide the service to the building owner and the owner then has to calculate the amount charged to each unit. Some other services, such as electricity, internet and phone service may be charged to individual units through separately installed meters and connections.

Be aware of the following:
In Germany you are also as expat obligated to pay this service even if you not using a tv or radio!!!
Cable/Satellite Television (Kabel/Satellite Fernseh)
Apartments - In areas where cable television service is available it's quite possible that an apartment building has a main cable connection box that allows the landlord to let renters have access to cable TV in individual rental units. Cable TV fees can be part of the Nebenkosten or paid directly by the renter to the cable provider. It normally depends on the system that is set up and the agreement with the landlord. It the former tenant had the service and paid the provider directly, it would be necessary to have the account transferred to the new tenant to continue service. Fees are normally paid monthly by standing payment order.

Hope this is a better help for you.
You could also check this link https://blogs.transparent.com/german/th … n-germany/

Good luck and God bless.

As Henkjan correctly described above, "kalt" means pure rent without any utilities included, "warm" usually means some or all utilities included - which ones depends largely on the individual rental contract, so ask the landlord:
- fixed items that the landlord must pre-pay are almost always included in "warm", e.g. insurance, tax, maintenance, cleaning of common areas, garbage collection, etc.
- heating is normally included as monthly pre-payment, with your actual usage calculated yearly (and then you may get some money back or have to pay some more) - it is mandatory in Germany (by law) to charge heating costs by actual usage
- water may be included as lump sum, as pre-payment (like heating) or not at all
- Internet and cable TV subscriptions may or may not be included
- electricity and phone are only rarely included
- TV license fees are never included, because the respective agency always charges it to the residents directly

I do not know the term "Vormerkschein".
There are some (too few) apartments available to the poor at subsidized rents. They are called "Sozialwohnung". To be eligible for those, you need a certificate by the respective government agency ("Wohnberechtigungsschein"). Maybe you meant this?

(Source: I am landlord myself, so know these things.)

Vormerkschein only for Austria, in Germany this is not been used or valid, basically this is a preregistration still been used from Vienna and is intended to make it easier for people who have lived in Vienna for a long time to find an apartment in the city. On July 1, 2015, the ticket was replaced by the Wiener Wohn-Ticket. Existing tickets, however, remain valid.