A bar bolt lock, also known as a Charley Bar, will prevent burglars from prying open your windows.The bar fits across the window on brackets installed on each side of the glass. It can be folded up flush with the window frame when not in use. These are most often used on sliding glass doors because, while they will prevent someone from prying open the window, they won't stop someone from popping the window out of the track.
Dead bolt window sets are installed at the bottom of the window and will deter almost any burglar. They are simple to install with common household tools and are relatively inexpensive. Since the lock housing is located on the window jam and the bolt goes into the window frame, the window can't be lifted off its track or be pried open.
One of the easiest and least expensive ways to secure your windows is with a through-the-frame pin or screw. Install the screw about halfway into the upper track of the movable glass panel. The window should just clear the head of the screw when you open it. These screws will prevent the window from being lifted out from the outside.
Like dead bolts, sash stops consist of a steel post that fits through both the inner and outer frame. They are installed on the side of the window frame about 6 inches from the bottom of the window. Sash stops allow the windows to open just enough for ventilation, but they completely thwart a burglar short of breaking the glass.
According to security consultant, Chris McGoey, windows are left open and unlocked more than doors, making them especially attractive to burglars. Don't store the key to your locking device in the window. When you install your locking device, ensure that someone can't reach through the open window and remove it. Crime prevention or alarm decals on your windows can deter a burglar from choosing your home to rob.