1) The world's largest volcano, Mauna Loa in Hawaii, is also one of the most active.

2) The first commercially available digital camera, the Dycam Model 1, was introduced in 1990 and had a resolution of 376 x 240 pixels.

3) Mountains are important water sources, as they capture and store precipitation, feeding rivers and supporting ecosystems downstream.

4) The first commercial mobile phone, the Motorola DynaTAC 8000X, was released in 1983 and weighed nearly 2 pounds.