Invisible
Source Player Core pg. 426
A creature with the invisible condition (by way of an invisibility spell, for example) is automatically undetected to any creatures relying on sight as their only precise sense. Precise senses other than sight ignore the invisible condition. You can Seek to attempt to figure out an invisible creature's location, making it only hidden from you. This lasts until the invisible creature successfully uses Sneak to become undetected again. If you're already observing a creature when it becomes invisible, it starts out hidden since you know where it was, though it can then Sneak to become undetected.
Other effects might partially foil invisibility. For instance, if you were tracking an invisible creature's footprints through the snow, the footprints would make it hidden. Throwing a net over an invisible creature would make it observed but concealed for as long as the net is on it.
Other effects might partially foil invisibility. For instance, if you were tracking an invisible creature's footprints through the snow, the footprints would make it hidden. Throwing a net over an invisible creature would make it observed but concealed for as long as the net is on it.