Campgrounds don’t always have the cleanest water, so it’s good to filter for both health and taste.
Exterior water filters are the most-common - you attach it directly to your hose
Under-sink water filters attach to your cold water line somewhere inside the RV, typically by the sink. These are a bit more involved to install, but easiest in the long-run.
Container water filters are just a pitcher that filters the water - you may have used one of these in your home