Grand Duke -- I don't think anyone mentioned that there are a variety of optional tests for USA high school students to take that will show their ability in specific subjects. They are usually taken in conjunction with the SATs. A student who wants to attend a highly competitive school may also offer his/her scores in A.P. tests to look more interesting to that school. Frequently these courses will allow the student to "test out" of introductory classes while getting credit for the work. This is the list of various Advanced Placement tests currently available.
Computer Science A
Computer Science AB
German Language Comparative Gov't & Politics
U.S. Gov't & Politics
The CLEP (College-Level Examination Program) also tests for subjects beyond the basic SATs.
Typical timeline for a student in the US:
K-12th grade resulting in a High School diploma at age 18
4 years at a college - Bachelor of Arts or Sciences
1-2 years -- Master of Arts or Sciences
2 years -- PhD in a specific field (Literature, Biology, etc.)
or 3 years -- LLD (law)
or 4 years -- MD medical, DDS or DMD (dental)
Other common scenarios... GED (General Education Diploma) instead of a standard H.S. diploma which is awarded after the student passes a comprehensive test.
Running Start -- Student's last two years of High School & first two years of college are taken simultaneously, with dual credit so that the student receives an AA (Associate of Arts) degree from a community college + H.S. Diploma. The student may then continue his/her education at a 4-year institution, resulting in a BA or BS, etc. as above.
There are also many career-specific training programs through technical institutions, community colleges, vocational colleges and apprenticeships. Sometimes a H.S. student will begin to this training while continuing to attend H.S. part-time for the last two years.
Relative asked how many receive scholarships. I'd estimate (based on my five years of volunteer work with my school district's scholarship program) that a minimum of 50% receive some assistance, but frequently that may be a very small percentage of the real costs. I estimate that a "full-ride" or "toothbrush" scholarship is given to less than 10% and most of those are for sports. An additional 5-10% receive substantial assistance through military programs like ROTC (Reserve Office Training Corps).