From BlenderWiki

Size and position

(graphic way)

Toggle in and out

• Click on the small gray triangle top-right in the view to openup the Properties panel, or in the View menu choose "Properties"
• This opens a gray tab on the right of the view, where you can find the view properties.
  This panel is modal, that is: it depends on the mode you selected in the view
• Click again to toggle in and out the view

(shortcut)

Alternatively, press N

Resize

Click and drag the triangle to resize the properties panel

You can also get the panel in and out by dragging the triangle:

• If the panel is hidden, drag it in the view.
• If the panel is in the view, drag it away from the view.

(to be written)