A: For that, we have gravity to thank! People and the planet Earth both have masses, and so there’s a gravitational force of attraction experienced between the two. But because the Earth has such a huge mass in comparison to average people, this gravitational force acting on people is much stronger. And not only that, the Earth’s own gravitational field - and hence the force - acts towards the Earth’s center, therefore no matter where on Earth we’re positioned, the attraction we feel will always be directed towards the Earth’s core. Because of that, our feet are always planted to the ground.