If camouflage is an art, then Mother Nature is a master artist.
Generally, camouflage in the animal kingdom is an evolutionary adaptation that serves to help animals to survive long enough to reproduce. But specifically, camouflage can help protect a critter from predation by blending in with its environment, making it more difficult for predators to see it. Or, camouflage can aid an animal in being a successful predator by making it difficult for prey to notice it and thus to avoid it. Both of these strategies aid in in the survival of the camouflage-ee.
The moth below has obviously found a great place to hide from predators like birds which would otherwise find it to be a tasty morsel.
The crab spider below hides in plain sight on the underside of a leaf. Its camouflage not only helps it to hide it from predators, but also, because it is a predator itself, to hide from potential prey that may wander too close.
The American Bullfrog below also uses its coloration to hide from both predators and prey. Its green and brown coloration matches the brown mud and green foliage it finds itself in.
The brown marmorated stink bug below closely matches the bark of the tree it is on. Even in closeup, you can see how difficult it is to pick this bug out of the background!
Below is a spider that appears perfectly at home amidst the gravel, sand, soil, and miscellaneous detritus of our driveway.
Can you tell what critter is camouflaged in the photo below?
How about now?
Of course there are uncountable numbers of other animals that use camouflage, but I've only included those that I've photographed myself.
And keep in mind that many animals we humans find easy to pick out of the background may be using camouflage that we can't notice. That's because not all animals see the same colors as we do, so for example, what may be camouflaged to a deer is not camouflage to people. Deer hunters who wear bright orange camo clothing know this well: the deer can't see orange, but people can.
AND, what might seem camouflaged to us is as plain as day to some other animals. Some critters, like bees, can see ultraviolet while humans cannot. Finally, it may be worth noting that no matter how good an animal is visually camouflaged, some other critter has a solution: like snakes that detect body heat, or like a fox that can smell their prey, or a bat that can use sonar to "hear" where you are!
Finally, and this is the last "finally", I promise, the only way to hide from a mosquito is if the dastardly little bastard is dead. But seriously, you have to use a repellant like DEET even though those repellants don't really "repel" those little blood suckers; instead they work by confusing the three sets of sense receptors that these miniature vampires have. Besides being able to see you, mosquitoes can 1) detect the carbon dioxide you breathe out; 2) detect the lactic acid that your skin gives off; and 3) detect the heat of your capillaries and blood vessels in order to zero in on a particular blood rich site.
So, to completely hide from every critter on Earth, tell NASA that you want to book passage on the next flight to Mars!
Isn't nature amazing??!