Without equations, most of our technology would never have been invented. Of course, important inventions such as fire and the wheel came about without any mathematical knowledge. Yet without equations we would be stuck in a medieval world.
Equations reach far beyond technology too. Without them, we would have no understanding of the physics that governs the tides, waves breaking on the beach, the ever-changing weather, the movements of the planets, the nuclear furnaces of the stars, the spirals of galaxies - the vastness of the universe and our place within it.
There are thousands of important equations. The seven I focus on here - the wave equation, Maxwell's four equations, the Fourier transform and Schrödinger's equation - illustrate how empirical observations have led to equations that we use both in science and in everyday life.