Proportional Editing (The "O" Key)

Move geometry like clay.

The Workflow

1. Press O to toggle Proportional Editing.
2. Select a vertex and press G to move.
3. Scroll your mouse wheel up/down.

The Technique

The grey circle indicates the Falloff. Every vertex inside that circle will move with your selection, but with diminishing influence. Use this to create hills in a landscape grid or reshape a character’s skull without moving verts one by one.