For added security for your home, you may wish to consider fitting window grilles, at least to your most vulnerable windows, like basement windows or those overlooking an alleyway, for instance.
In case you have visions of your home beginning to look like Wormwood Scrubs, then you might want to think again. Whilst it is true that a lot of security grilles are merely functional and practical, suitable for shops and business premises, there are companies which install attractive designs suitable for domestic properties.
External grilles are fitted outside the window and are usually constructed of some kind of metal or wrought iron with fixings usually fitted straight onto the brickwork of the surrounding wall. Permanently fixed grilles should never be fitted to a window which may need to be used as an emergency exit.
However, it is more common to have internally fixed grilles which are either fitted into the recess of the window or onto the window frame itself. The most practical designs are hinged which allow easier access for cleaning.