Here's a breakdown:

* Hypocenter (Focus): This is the exact point underground where the earthquake originates. It's the spot where the rupture of the Earth's crust begins.

* Epicenter: This is the point on the Earth's surface directly above the hypocenter. It's often the area where the earthquake's effects are felt most strongly.

So, while "epicenter" is commonly used to refer to the location of an earthquake, it's important to remember that the actual origin point lies beneath the surface at the hypocenter.