Moore’s Law is the observation that the number of transistors and other components that can be economically placed on a single integrated circuit grows at a steady exponential rate, roughly doubling every year in the original formulation and later restated as roughly every two years. It is not a law of physics but an empirical trend about manufacturing economics, and for decades it held closely enough that the entire semiconductor industry organized its planning around it.
The idea comes from Gordon Moore’s 1965 article “Cramming more components onto integrated circuits,” published in the trade journal Electronics. In the paper Moore wrote that “the complexity for minimum component costs has increased at a rate of roughly a factor of two per year,” and projected that “over the longer term, the rate of increase is a bit more uncertain, although there is no reason to believe it will not remain nearly constant for at least 10 years.” That ten-year projection, that complexity would climb from about 60 components to roughly 65,000, proved remarkably accurate.
Moore’s deeper point was economic. For any given manufacturing process there is a number of components per chip that minimizes the cost per component, and that sweet spot keeps moving toward higher complexity as the technology improves. He argued in the article that “integrated electronics will make electronic techniques more generally available throughout all of society, performing many functions that presently are done inadequately by other techniques or not done at all.”
Over time Moore’s Law became something closer to a self-fulfilling roadmap than a passive prediction. Chipmakers, equipment suppliers, and software developers all set their plans on the assumption that transistor counts would keep doubling, and that shared expectation pushed everyone to invest in the research and tooling needed to make it come true. The result was the multi-decade march from a few thousand transistors to billions on a single die.
The law’s exponential pace is why a modern microprocessor can hold orders of magnitude more logic than the integrated circuits of the 1960s, and why computing power became cheap enough to put into phones, cars, and appliances. It also set up the great question of the late 2010s and 2020s: what happens as the doubling slows and the physical limits of shrinking transistors come into view.