Yes, when you take a step, your foot exerts a force against the Earth. This is due to Newton's Third Law of Motion, which states that for every action, there is an equal and opposite reaction.

Here's how it works:

1. You exert a downward force on the Earth: When you push off the ground with your foot, you apply a downward force on the Earth.

2. The Earth exerts an equal and opposite force on you: According to Newton's Third Law, the Earth will exert an equal and opposite force back on your foot. This force is what propels you upwards, allowing you to take a step.

Important Note: While your foot exerts a force on the Earth, the Earth is much more massive. This means the Earth's reaction force will have a negligible impact on its motion. You, however, will experience a noticeable upward force that allows you to move.