Advanced placement coursework is designed to be difficult for average high school students. Most AP courses are sufficient preparation for the AP exams that students can opt to take at the end of the year. If students do well on these exams, they can pass out of these introductory courses in college.
The academic benefit of AP coursework, aside from being able to pass out of college courses with good AP exam scores, is that students get 1.0 extra GPA points particularly for that class. An A+ or A in regular US History, for example, will factor in 4.0 GPA points to a student's grade; however, an A+ or A in AP US History would factor in 5.0 GPA points, which would noticeably improve that student's grade.
Most students who apply to incredibly selective undergraduate school colleges and universities like Stanford University and MIT take between four and eight AP classes in high school. They do this for various purposes: 1. to boost their GPA 2. to give them a sense of college class rigor 3. to allow them to pass out of corresponding classes in college