Blinking helps clean and lubricate the cornea.
Why it is true
Each blink spreads a film of tears over the cornea, removing dust and microorganisms and keeping the eye surface moist. We blink about 15 to 20 times per minute, and this frequency increases when we are nervous or using screens.
Source: Journal of Anatomy
Would you rather be asked first?
This is the reading side of the site, so the answer is in the sentence above — that is the whole point of it. Test yourself works the other way round: the question comes on its own, and the fact and the explanation only appear once you have answered.