What are boundaries called in Earth's surface?

Answer 1

The earths surface is split into tectonic plates, the boundaries are called fault lines which is where volcanies emerge and mountains are created

Answer 2

Boundaries on Earth's surface are called geographic boundaries. These boundaries can be natural, such as mountains, rivers, and Coastlines, or they can be artificial, such as borders between countries or states. Geographic boundaries help define territories, separate landforms, and demarcate political jurisdictions.