The primer as the name itself suggests, the primary layer that ready to receive paint. It is nothing but paint without pigment. It lays the foundation for your paint job and increases the durability of paint. Ultimately, it will enhance the life of paint film. It is applied to both the interior as well as the exterior surfaces. Therefore, primer is absolutely necessary before painting.
Applying primer before paint coat will provide extended coverage to paint and may provide a smoother finish appearance. It exists in many forms and serves a variety of functions. There uses around your home are limited only by the surfaces that you want to paint.