When turning a screw, apply pressure to the line, lines or other shapes on the head and rotate the threaded shaft to drive the point at which surface you are attaching. Over time, these lines or shapes can be damaged by pressure that does not spin the screw, if it e.g. stuck or already fully inserted.
Tightened screws have had the shape of their heads so clever that a tool such as a screwdriver or drill can not connect with them to turn the fastener with sufficient pressure. This can cause them to stick partially or completely embedded in the surface to which they connected.
A common method of removing a stripped screw is to grasp it with some pliers and turn it by rotating them counterclockwise. In some situations, you may be able to use a hammer claw, but that method tends to be much dirtier and more difficult.
To prevent screws from loosening in the first place, work carefully when using a screw ̵