What observation about integrated-circuit complexity became known as Moore’s law?

Moore’s law is a prediction made by American engineer Gordon Moore in 1965 regarding the complexity of integrated circuits. Observing that the number of transistors per silicon chip had been doubling annually, he extrapolated this trend to predict that the number of components would continue to double each year over the following decade.123

In 1975, as the growth rate began to slow, Moore revised his estimate to a doubling period of two years. Historically, the number of transistors has doubled approximately every 18 months. This dramatic increase in circuit complexity has been made possible by the steadily shrinking size of transistors, which have evolved from millimetre-scale components to features measuring only tens of nanometres. While often referred to as a law with the certainty of Newton’s laws of motion, it is more accurately described as a technological observation and prediction that has guided the semiconductor industry for decades.123