To perform many types of operations on a polygon mesh you must first select the related polygon components you want to modify.
The following table describes techniques for selecting the various types of polygon components.
For example, if you select an edge and try to delete vertices, Maya automatically selects the two end-vertices of the edge and deletes them. However, if you select those two end-vertices and try to delete edges, Maya selects all edges that touch either of the two vertices and deletes them.