Groups are an easy way to show and hide sets of pins from your map. Any pin can be placed into as many groups as you'd like. If all the groups that a pin is in are hidden, that pin will not show. If you require a group, then any pin that is in that group will show on the map. Your lead stages (from the leads page) will also show up as groups so that you can see pins from each stage on your map. In addition, if you create any territories they will show up as a group that you can control here as well.