An RTA is a Rebuildable Tank Atomiser. It combines the RDA with a traditional tank. So you don’t need to manually drip the e-liquid. You can store liquid in the tank and immerse the wicks in it instead. In some RTAs there is also a function where you can drip liquid onto the wick. By pressing down on the drip tip in the same way you would with an RDA. You still get the benefit of being able to use different wires, And personalise your coils to your liking without having to drip so often.
To be classed as an RTA the equipment must have the same e liquid capacity as a tank and have a rebuildable deck for home-made coils much like a normal RDA. Essentially RTAs are a great option for those who want the benefit of a dripping experience without having to top up your wicks as frequently.