If you're asking what it does, it doesn't DO anything, it just IS.
If you're asking what it's due TO, that depends on what specific illusion you're talking about. Some of them are due to our expectations, some are due to idiosyncrasies in our physiology or psychology, and some of them are due to actual physical phenomena.
No, it is not an optical illusion.
A mirage is an optical illusion which is caused by atmospheric conditions. This is often due to the refraction of light from the sky by heated air.
yap.. its just an optical illusion
All mirages are optical illusions but all optical illusions are not mirages.
OpTiCaL ILlUsIoN WaZ MaDe fOr ArT AnD FoR tHe InJoyMeNt oF thE PeOpLE
Optical illusion challenges will increase sharpness of your brain. Also the increasing visual literacy is also possible through optical illusion challenges.
It is in your question already. An illusion will never be real. If it was real then it would be no illusion. Optical illusions are in a way real. They are real optical illusions. We can however not fake an illusion because the illusion is fake from start.
Bored Panda is a great website which offers a number of different optical illusion pictures. You can also find optical illusion pictures from Yahoo! Images.
NO
The fog created an optical illusion.
The Müller-Lyer illusion is an optical illusion consisting of a stylized arrow.
its an optical illusion