Type Kerning and Kerndown

Above: The three primary methods of kerning

"Letter spacing should not be mechanically equal but must achieve equal optical space" Tschischold, J.

The whole look and feel of an image or piece of text can be completely overhauled by making subtle or extreme adjustments to the kerning of the type. 

Monospace typeface: One which has a standard fixed width between letterforms which is difficult to alter