“What is Rent Control?”, you ask.
Rent Control is how some governmental policies that prevent the Landlord from abusively raising the rent are called in the real estate world.
"Rent control in NYC!" is how TV producers excuse themselves when asked how those twenty-something sitcom characters – like the ones on “Friends” - are able to afford to live in such huge apartments. But because of the omnipresent Rent Control in NYC broadcasted by Television and Movies, many people think that the whole country has it and that is not true. Not every state has rent control laws. And the ones that do, normally don’t impose those regulations over every single rental property. Rent Control is usually a tool against gentrification used only in communities where the demand for housing is too high - like NYC.
A Landlord with a house (or an apartment) under those rent laws basically has determined by the government when (and by how much) he/she can increase a Tenant's rent. This prevents the Tenants from having a bitter surprise when the time comes for the contract renewal.
Note: the Landlord is not stuck forever with the Tenant. He/She can reach out to the market and find a new Tenant willing to pay his/her overpriced rent, sure. However, he/she will have a hard time finding this new Tenant, because other properties in that same area are not costing as much, thanks to those governmental policies. If the new Tenant knows this, he/she will probably negotiate around that. Also, hopefully, the current Tenant will have done a good job on his/her rental contract and will have made a clause where he/she has the right to cover the offer and/or other tactics to keep himself/herself inside that property.