Answer : Rubber sucker is something which is mainly used in toys. They are also used in sunlight blockers, suction clamps, suction cups, etc. It is generally used for a temporary period where you need to stick something. It is used as an alternative to glue. So, you can use it when you do not wish to use glue.
When you are holding and pressing the suckers against the surface, it automatically squeezes out the air behind it. In this way, they will stick to the surface perfectly. The atmospheric pressure outside the suction has it perfectly against the wall or a smooth surface.