"RTV (room-temperature vulcanizing)" means that type of silicone cures at room temperature, and doesn't require additional heat to cure.
"Heat curing" is required for some silicones. Also, some silicones can benefit from "post curing", which is a semi-optional step where the silicone is heated in an oven at a higher temperature for a while.
There are three different cure systems: platinum-cured, condensation-cured, and peroxide-cured.