Muntins, also referred to as muntin bars or muntin grids, are a decorative option on windows used to make one pane of glass look like multiple panes framed together. This can have the effect of making a modern window appear more colonial or of a more classic design.
Muntins can be placed over the glass pane on inside of the house and the outside of the house. They can also be in between the panes of insulated glass.
Contoured, or Ogee, muntins complete the illusion by resembling wood trim.