Personally, I do not think that it is necessary to have an internship prior to college. From my experience, it is important to build strong study habits in high school to prepare for your four years of college. I would say it is necessary to have at least one internship that relates to your major, before you graduate from college. During your time in high school you should figure out what your strengths and weaknesses are so that you are able to utilize them in college. I think that having an internship prior to college would look fantastic on a college application, but it is not necessary. College boards look for other attributes/characteristics as well. They look for leadership positions, clubs, and more. As long as you can work hard at your field, you will be fine in the future.