Newton’s second law defines what acceleration is. The rate of velocity or velocity per unit time is a way to think about it.
To go from the steam engine to widespread usage of the telephone took nearly a century and a half.
However, to go from the internet to widespread use of smart phones took around a couple of decades.
At this accelerated pace, when will self driving cars and trips to Mars become commonplace? The answer is: in the not too distant future.