Not all patios have floors, but you might want to floor yours so it can be used more like a room. Without a floor the base of the structure will eventually get wet, no matter how dry your climate is. This means that the furniture or anything else sitting under the patio will also get wet from the ground up.
Chair and table legs made of timber will end up rotting, while cupboards will the ruined, especially if they are clad with MDF, which absorbs moisture and expands, then falls to pieces. So what kind of floor will you have for your patio? Much depends on how you want to use it. If it is just to park the car under, there is no real need for any floor.
But if you want to use it during rainy weather or put furniture in it, then a floor of some kind is advisable. Here are 7 suggestions for a patio floor.