A junior student is typically a student in their third year of high school or college. In high school, juniors are usually around 16 to 17 years old, while in college, they are often around 20 to 21 years old. This year is important for academic development, as students prepare for graduation and post-secondary education options. During their junior year, students often take more advanced courses and may begin to focus on specific subjects related to their interests. They may also start preparing for standardized tests like the SAT or ACT, which are important for college admissions.