Many people don't appreciate the humble transistor. The little switch that makes up the building blocks of so many electronic devices. With an external influence it flips its output from one position to the other to change the flow of electricity much like a light switch. A light switch that can be as small as one nanometre. That's a billionth of a metre. The diameter of a helium atom. You could stack about a hundred thousand of them on top of each other to match the width of a human hair.
Back in 1971, the Intel 4004 integrated circuit had some 2,300 bloated 10,000nm transistors in it. Today, some Intel i7 processors contain over a billion tiny 14nm transistors.
Gordon Moore, a co-founder of Intel, once mused (and published) that the number of transistors in an integrated circuit would roughly double every two years. This became known as Moore's Law and has held up fairly well since its creation in 1965, despite being obviously unsustainable.
In 2014, Forbes estimated some 2,913,276,327,576,980,000,000 transistors had been created. That number is of the same order as grains of sand on all the beaches in the world.