Windows should be kept locked when not in use if you are concerned about security. Locking them protects against intruders, and it also creates a secure indoor environment for children. You should know how to properly unlock your windows for ease of access and so that in the event of an emergency you can get them unlocked and open quickly.
Swing the lock lever to the "Unlock" position. Sometimes this type of lock features a picture of an opened padlock near the "Unlock" position, and a closed padlock near the "Lock" position. Slide the window open by pushing the sash in the appropriate direction.
Check the window track for other locking mechanisms. Some sliding windows feature a safety catch or ventilation lock that stops the window from opening more than a few inches. This is an excellent safety feature for homes with children, as well as protection against intruders. Flip the catch up or over, positioning it perpendicular to the frame, and slide the window open.
Insert the safety key into a keyed turnbuckle lock and turn to the "Unlock" position while squeezing the lever. Remove the key and store it in a safe place.
Swing a hinged wedge lock out of the way of the window track if your windows are equipped with this type of lock. Then push the sash open.
Remove screws or bolts on any key track stops installed on your sliding window. These work like ventilation locks but feature a key for added security. Remove the key and track stop and slide the window open.