For residential window clings, the film is applied to the inside of a glass surface, while the majority of vehicle clings instruct that decals are to be applied to the exterior. The side of the cling that has the adhesive determines where the cling is applied.
Most products include an installation guide to assist in the application. While there are variations, the majority of clings and decals are similarly applied. If the cling is said to be removable or reusable, the decal affixes on the inside of a window; otherwise, the cling is commonly applied to the outside of the window.