The polish can be applied directly to your nail plate or over acrylic or traditional gel nail extensions.
They can also provide some strength to your nails, although results will depend on how fragile your nails are to begin with.
Removal & Care
Ideally you should have your gel nail polish removed by a professional nail technician, who should remove them by soaking in acetone then gently and careful buffing and scrapping, this should avoid any damage to your natural nail plate.
If you are going to remove them yourself, apply a generous amount of cuticle oil (or any oil) to your fingers then soak them in acetone until removed, then gently wipe the nail plate clean and wash your hands, moisturise well to finish.