What you do in the summer can make a significant difference to where you can go to college. At the most selective universities, admissions officials do consider how you used your summer vacations. This used to mean that many students went on service trips to other countries, where they do community work. That is still an option, but there are now many more types of summer programs for high school students you can consider.
Understand the admissions factors college admissions officials consider in an student to build a great application.