Which technology has become the primary way in which we interact with our tablets and smartphones?

The answer to this question is Touch screen
Ten years ago, all phones are using keypads. Touchscreens actually had been invented in the 1970s, but it's started tend to be broken easily.
In recent years, touch screen technology had become more and more resistive and could be used in almost all tablets and phones

Accumulating more land so that your country can continue expanding without running into problems such as overpopulation