I'm a beginner. Everything was going along fine. I was using click, hold, grab to pull and push on vertices without striking the G key. For some reason now it's not working and when I hit the G key a small dotted yellow line appears and extends and contracts with my mouse movement. What did I do?
In Blender you can begin to grab either using the right mouse button or the G key.
After that you can move the wanted vertices, but if during this movement you hit G again, the movement is limited to the edges connected to the displaced vertex.
In complement, that can be used with more than one vertex, here are some behaviors :
I figured out what I did. I accidentally hit the magnet icon in the header. whoops
and.....I probably hit the g key twice too. Having the best time. :-P