in plate tectonics, the boundary between two plates that are diverging (spreading apart)

In plate tectonics, a divergent boundary (divergent fault boundary or divergent plate boundary), (but also known as a constructive boundary or an extensional boundary) is a linear feature that exists between two tectonic plates that are moving away from each other. These areas can form in the middle of continents but eventually form ocean basins. Divergent boundaries within continents initially produce rifts which produce rift valleys.