Why actually is the sky blue...

?

because.

Its amazing how much information can be found online in just a few seconds for anyone willing to actually search. I just typed your question into the search bar and look what I found in about 3 seconds:
http://www.sciencemadesimple.com/sky_blu…
http://spaceplace.nasa.gov/blue-sky/redi…
http://science.howstuffworks.com/nature/…
http://en.wikipedia.org/wiki/Why_is_the_…

These are just a few I found.

I think it's because our upper atmosphere is mostly Nitrogen.

-It has nothing to do with water vapor.

Why do I get a thumb down? I took a ******* atmospheric science class and I have the book right here. Patti might be correct with the bending thing, but I know for certain that nitrogen is blue.

It is because when the colour spectrum (colours of the rainbow) is scattered, BLUE is bent the most, which is scattered the most, making the sky look blue more then any other colour.

Because I didn't want it to be yellow... :)

The same answer to this question any other time... Because the water vapor in the sky refracts the suns light, and we see the blue light. And, before you ask, the ocean is blue because it is a reflection of the sky.