Windows tend to be the first target for burglaries, but are rarely broken in order to get into the house due to the amount of noise they produce. Many times a burglar will simply find an open window that has no lock. A window lock of good quality tends to prevent this, however, and will further
secure your home against burglaries or any number of break-ins. This is why numerous people will end up buying window locks if their house has easily accessible windows. Once you arrive home with the lock, however, it may prove difficult to get it on the window properly. This can be due to the complexity of the lock, or the person is not sure where to put it, or perhaps the instructions are missing.
In some cases, the window itself may prove to be hostile. These types of windows can be replaced, or the frames fixed so that the lock can be fashioned on it. In cases where both prove impossible, the last resort is to find a lock specifically for the window type as opposed to a common lock.
For a regular window lock, there are normally special screws that come with it so that when you screw it down it wont break the glass, or come near it. The regular locks range from key locks to a simple window latch, but are effective in making it difficult to open. It's simple to fit a latch on to the window; just place the lock on top of the
first frame, and the latch on the bottom of the one behind it (normally it's the stationary window, as it doesn't slide down), then screw them down so that they are right next to each other in the middle of the window. If the screws are, in fact, longer than the frame, you should purchase smaller ones at your local hardware store. Otherwise you may hit the glass and/or weaken the frame enough for the lock to be ineffective. This is a generally bad idea since it will defeat the purpose of placing a lock on the window to begin with.
This would be a simple example of how to fit a window lock on your average window. Other types of window locks include (but are not limited to); Sliding window lock, Keyed sash lock, Window latch, Sliding, window latch, Keyed patio door lock, Patio door pin, Patio door bar, Deadbolt, and key-card lock (this is rarely used on windows).