What are primers? I hear that some Tamiya models come with primers already applies for an "easy" finish. What do I do with primers? Thanks.

primer makes the paint stick better to the model, and clears soem unwanted imperfections, ive noticed it helps a lot when you used putty, and it gives the paitn a good color sometiems whne you have different colored plastic, once your paint the tone of the base coat will slightly change

Frank