Plate tectonics is the framework in which geologists study and understand the inner workings of the earth. It provides us with a way to tie together what once was considered unrelated geologic processes and events. Consider the origin of the ocean basins, shifting position of the continents, where volcanoes erupt, where earthquakes happen, and why mountain ranges are found where they are; all of them are explained by plate tectonics. The name itself is derived from the terms for two important components of the model. The term plate refers to the large pieces of the earth's lithosphere that are in constant motion; you may see them referred to as lithospheric plates. Tectonics is the branch of geology dealing with how continents form, change, and move over time, plus the study of mountain-building episodes.