Tectonic plates interact at places called what?

Tectonic plates interact with each other at places called plate boundaries.

Tectonic plates, in the simplest terms, are large fragments of our lithosphere (which consists of crust and the upper mantle of Earth) that are in constant motion. All the continents and oceans lie over these plates. During their motion, these plates interact with each other at plate boundaries. 

There are three types of tectonic plate boundaries: divergent boundaries, convergent boundaries and transform boundaries. Divergent boundaries are obtained when the tectonic plates are moving away from each other, while convergent boundaries result when plates are moving towards each other. In comparison, transform boundaries result when one of the tectonic plates is sliding underneath the other. 

The plate boundaries are associated with events such as volcanic eruptions, earthquakes, and the formation of new crust and mountains, among others.

Hope this helps.