Denise and Kory-
I've provided two links below, for your reading.
If you look around I think you'll find that most RV house batteries are flooded-cell or AGM (Absorbed Glass Mat) types. Few, if any, are gel type.
Flooded-cell batteries are less expensive to buy. They require that you inspect and top up water levels in the cells on a regular basis. To make this chore easier, some folks install a tubing system, such as the Pro-Fill
AGM batteries are more expensive to buy, but are basically maintenance-free.
Having bought a set of new batteries, you may want to have them last as long as possible. One gizmo that can help with that is a battery monitor. Think of it as a "fuel gauge" for your batteries. I like the monitor from Trimetric
, but others are available.
Battery Basics: A Layman's Guide to Batte | BatteryStuff Articles
Lead-based Batteries Information â€“ Battery University
(also read article BU-201a)