Some of the situations that can occur in Blender, is when we want to move a vertex along an edge line. The thing here is that this edge line is not going in same directions as the default GLOBAL XYZ. We see this when we look at the floor grid underneath. That’s the main grid in Blender.

Now to actually move a vertex the way shown, we need to change the default GLOBAL to NORMAL.

And now we can move that point by hitting short keys G + Y, and move the mouse.