Here's why:

* Plate Boundaries are Zones of Stress: The Earth's tectonic plates are constantly moving, grinding against each other, pulling apart, or colliding. These interactions create immense stress and pressure along the boundaries.

* Fault Lines Form: The stress along plate boundaries leads to the formation of fault lines, which are fractures in the Earth's crust. These fault lines act as release points for the built-up pressure.

* Seismic Activity: When the stress becomes too much, the rocks along the fault line suddenly slip past each other, releasing energy in the form of seismic waves, which we experience as earthquakes.

Examples:

* Ring of Fire: The Pacific Ocean's "Ring of Fire" is a prime example, with a high concentration of earthquakes due to the interaction of multiple tectonic plates.

* San Andreas Fault: This fault line in California marks the boundary between the Pacific and North American plates and is responsible for numerous earthquakes.

While most earthquakes occur near plate boundaries, smaller earthquakes can also happen far away from these boundaries. This is usually due to:

* Intraplate Earthquakes: These earthquakes occur within a tectonic plate, often triggered by the stress from nearby plate boundaries.

* Human Activity: Mining, dam construction, and other activities can induce small earthquakes.

In summary: While earthquakes can happen anywhere, the vast majority occur along plate boundaries due to the immense stress and pressure generated by the movement of these tectonic plates.