Moore's Law is a term attributed to Intel founder Gordon E. Moore who observed in 1965 that the number of transistors that could be purchased inexpensively and placed on an integrated-circuit doubles every year. He later revised this figure to every 2 years (1975).
The doubling period is often mistakenly reported as "18 months" or shorter,possibly due to being confused with estimates of overall computing power that DO double over that time period. However these estimates are based on additional factors such as increases in clock speed, size of cache memory or chip design. Moore's law is exclusively concerned with transistors density and nothing else.
For almost as long as there's been Moore's Law there have been commentators predicting its demise due to the supposed limits of engineering having been reached. The ability to increase the number of transistors available is due to reducing transistor size rather than increasing the size of the integrated circuit. As of the first half of 2012 the smallest commercially available transistors on a microprocessor are 22 nanometers (around 1.5 Billion transistors per chip), their 1965 equivalent were 100 micrometers (100,000 nanometers) with 50 transistors per device....