The domestic cat will hide under any available object. Cats like to place something over them when hiding. This seems to be more important than placing a barrier in front of them or behind them when hiding.
This may be because they frequently hide from people and people are very tall in relation to the domestic cat. The cat therefore sees the danger as coming from above and seeks protection from a threat above them.
A cat will hide for self protection when under threat of intimidation, aggression and/or violence against him or her.
It need not be an actual threat but one that the cat thinks is a threat. Accordingly, if the cat has been moved to new surroundings he will probably hide under something as he is unsure of the surroundings and what threats might be there. It is a precautionary measure by the cat. Over time the cat will be reassured that all is well and come out.
A cat sleeping in a quiet, out of the way, corner of the house is not a cat that is hiding. This cat has simply found a nice quiet spot for undisturbed and safe sleep.
Cats are very adept at hiding. Even in small places such as a home it can be very difficult sometimes to find a cat. You can be within a few feet of a cat and still not see her if she is hiding in a garden.
If looking for a cat that is hiding, look under objects. But this is not a guarantee of finding your cat as their behavior will vary from cat to cat and from circumstance to circumstance.