computers have become much much more powerful from the early days of 1960s. back then they filled up entire room or while floor n their computing power added up to less than whats on ur smart watch today.
the increase in computing power is tied to the advance in micro-electronics. the micro-electronics are called integrated circuits (ICs). the IC computing power has been doubled ever year leading to some very powerful computers today.
with the increase in their computing powers, computers have grown to be used on many different things. at first, it was only for military and secret govt projects. now computers are used to keep track of stock prices, manage production lines, monitor people health, calculate taxes and many many other applications.