As New York’s apartment prices skyrocket, rent control has become increasingly important in keeping the city affordable. Mayor de Blasio is a vocal advocate of the system, and just Wednesday defended the Rent Guidelines Board’s decision to freeze rents on one-year leases for stabilized units starting Oct. 12. But the system is also notoriously complicated. Thankfully, listings service Trulia has released a handy chart explaining the many rules keeping New York’s rents in check.

And here’s Trulia’s map of Manhattan neighborhoods with the highest ratio of rent-controlled units, Inwood and Washington Heights have the largest concentration of regulated units.

“This is primarily because these cheaper neighborhoods have more units that would rent for less than the $2,700 threshold (remember: units that rent for more than $2,700 become deregulated),” explained the Trulia report’s authors. “These days, finding units that rent for under $2,700 are rare in expensive neighborhoods such as Tribeca and the West Village, making it less likely for new renters to find rent-stabilized apartments.”