From BlenderWiki

[edit] Grab/Move

[edit] Description

One of the fastest ways to move things in 3D space is with G. Pressing this hotkey will enter the “grab/move” transformation mode where the selected object or data is moved according to the mouse pointer’s location. The distance from the mouse pointer to the manipulated object has no effect.

[edit] Options

LMB

Confirm the move, and leave the object or data at its current location on the screen.

MMB

Constrain the move to the X, Y or Z axis.

RMB or Esc

Cancel the move, and return the object or data to its original location.

Proportional Edit

The circle of influence, changed by WheelUp to make smaller and WheelDown to make bigger, is shown and will move vertices within that circle by the proportional method/falloff chosen.

See the rest of the Manipulation in 3D space section for additional options available within the transformation modes.

[edit] Rotate

[edit] Description

Pressing R will enter the “rotate” transformation mode where the selected object or data is rotated according to the mouse pointer’s location. This mode uses the angle from the pivot point to the mouse pointer as the angle for rotation, so moving the mouse further from the object/data will give more fine-grained precision (i.e. the mouse movement will affect the rotation less, for the same mouse distance moved).

[edit] Options

LMB

Confirm the rotation, and leave the object or data at its current rotation on the screen.

MMB

Constrain the rotation about the X, Y or Z axis.

RMB or Esc

Cancel the rotation, and return the object or data to its original rotation.

R (Trackball)

Pressing R while already rotating toggles the rotation mode between a single axis rotation (either aligned to the screen or around a certain axis) and a two axis, “trackball” rotation. In “Trackball” mode, the rotation of the object is controlled by both the X and Y location of the mouse pointer, similar to the trackball view rotation mode. This can be a quick way to rotate an object into place, without having to keep changing the view rotation while adjusting. However, it is more difficult to use than the simple rotation.

See the rest of the Manipulation in 3D space section for additional options available within the transformation modes.

[edit] Scale

[edit] Description

Pressing S will enter the “scale” transformation mode where the selected object or data is scaled inward or outward according to the mouse pointer’s location. The object/data’s scale will increase as the mouse pointer is moved away from the pivot point, and decrease as the pointer is moved towards it. If the mouse pointer crosses from the original side of the pivot point to the opposite side, the scale will continue in the negative direction, making the object/data appear flipped. The precision of the scaling is determined by the distance from the mouse pointer to the object/data when the scaling begins.

[edit] Options

LMB

Confirm the scale, and leave the object or data at its current scale on the screen.

MMB

Constrain the scaling to the X, Y or Z axis.

RMB or Esc

Cancel the scale, and return the object or data to its original scale.

AltS (only in Edit mode)

Scales along the selected normal direction.

See the rest of the Manipulation in 3D space section for additional options available within the transformation modes.

[edit] Precision

[edit] Description

Holding Ctrl and/or ⇧ Shift during a manipulation can be used to control the precision more finely.

[edit] Options

Ctrl (Snap)

Snap the transformation:

• For grab/move and scale, on 1 blender unit (or 10BU, 1/10 BU, etc., depending of the zooming view).
• For rotation, on 5 degrees step.

⇧ Shift (Precise)

Allow finer transformation control but not by precise values (i.e. by fixed steps).

⇧ ShiftCtrl

Snap the transformation on finer steps than with only Ctrl:

• For grab/move and scale, on 1/10 of the precision with only Ctrl (e.g. if with Ctrl you have steps of 1BU, with ⇧ ShiftCtrl you have steps of 1/10 BU).
• For rotation, on 1 degrees step.

[edit] Numeric transformations

[edit] Description

When doing a transformation, instead of using the mouse (imprecise work), you can directly pass a precise numeric value.

Hit - NumPad (on a French keyboard, the minus is under the number 6 key, so you must use the Numpad) if you want negative values, and then a numeric value. You can see the values in the header of the 3D View. If you were using an axis constraint (global or local), the value is applied to that axis. If there is no axis constraint and you want to choose which axis to control, you can use ⇆ Tab to switch from any of the axis (a cursor appears after the value). You can also return to a mouse control with ← Backspace.

[edit] Cancel transformations

[edit] Description

You can clear any transformation done in Object mode.

[edit] Options

AltG

Clear the location of the selection.

AltS

Clear the scale of the selection.

AltR

Clear the rotation of the selection.

[edit] Align

[edit] Description

Align selected objects to a specific Transform Orientation.