Why does the sky appear blue?

This is due to the phenomenon called Rayleigh scattering.Light coming from the sun is scattered from the gases and the molecules present in the air.Scattering of light varies1/ ƛ4,where ƛ is wavelength of the light being scattered.Since blue light has the lowest wavelength among other visible light,it scatters more as compare to red light.Blue light bounces from one particle to other particle and finally reaches to our eye.so every direction we see in the sky ,it appears blue.