Aligning vertices, faces, etc

When building a face from vertices (or just editing a face/object), is there an easy command to align vertices alone an axis (x/y/z or horz/vert)? One could always edit the raw coordinates of the vertices, but it would be nice if there’s an easy way to align them say for a vertical edge, etc.

along an axis: select a vertic to which you want to align. shift+s >>> cursor to selection. now select in the main header the size/rotate around corsur. size (S key) >>> select axis (x,y,z) >>> move youre mouse till the number on the header says 0.000.