A common example of diffraction of light is looking at an object that is partially immersed in water, where the object appears to be in a different place. Sound diffraction is usually not visible, but it is audible through walls or other solid objects.
Diffraction of light is the easiest to recognize, since it takes only a glance. Looking at something beneath the surface of the water is one example. In spear fishing, the fish appears to be somewhere it is not due to how the water affects light. Water droplets also diffract light in the same way.
The diffraction of sound is more difficult to pinpoint, but is most noticeable when solid items, such as walls or columns, are between the listener and the source of the sound. Sound also diffracts when it passes through water in a similar fashion to light. The waves slow down when passing through water, distorting the end result.
A good way to visualize diffraction is to imagine ripples or waves in water. If the waves are moving in a uniform line and the middle of the line hits a pole or wall, the waves bend around the obstacle and their form is changed, just like sound and light waves.