[MENTION=3586]MerricB[/MENTION] I also have problems with interpreting hiding. People tend to say that it's very clear, so perhaps it's my English languages skills causing a barrier to me...
Every now and then, I just can't help myself having the most basic doubt: what the hell "hiding" means, really?
Even in 3e era I remember actually sending an email to Monte Cook to ask for help, because in my mind "hiding" was primarily an off-combat action, it was a complex and sometimes time-consuming task of finding a suitable location (e.g. behind some curtains, inside a bush, under a pile of snow, or even amongst a crowd) and "blend" with it, so that someone arriving
later will not notice you're there, and won't be able to attack you or target you with a spell. Something had to at least partially block the view from you. A special "Hiding in plain sight" ability further meant to blend with the surroundings (like many animals do) so that you are effectively unnoticed without something blocking the view.
Instead, Monte Cook told me that in a RPG design, "hiding" usually refers to the action of
moving out of sight, which is slightly different, and which is why the action is often described together with movement (e.g. see his 3e Shadowdancer's abilities).
It's still not clear to me in 5e... we get the perentorial "You can’t hide from a creature that can see you" AND we get the "Hide" action in combat. How the hell are you supposed to hide (as "moving into a hidden position") during the middle of combat, where (with no facing rules) everybody can see you, unless you were hidden prior to combat itself?
All this is further complicated in a sniping scenario, where someone starts successfully hidden, attacks thus "reveals his position" but the text doesn't clarify if revealing your position means you're still hidden or not.