1) The fastest recorded serve in tennis was achieved by Sam Groth at 163.7 miles per hour (263.4 kilometers per hour) during a tournament in 2012.

2) The ozone layer, located in the Earth's stratosphere, protects us from harmful ultraviolet (UV) radiation.

3) The first computer mouse was invented by Douglas Engelbart in 1964 and consisted of a wooden shell and two metal wheels.

4) The first successful consumer digital camera, the Apple QuickTake 100, was released in 1994 and had a resolution of 640 x 480 pixels.