If you get an ROTC Scholarship right out of high school, It pays for Tuition, Books, Room & Board (For the college I'm looking at at least), and gives you a monthly stipend on $200-$400 was you go from freshman to senior. After your second year you have a commitment in whatever service the ROTC is, and if you complete all 4 years under the ROTC Scholarship you have a commision as an officer in whatever service and a commitment depending on career choice. And you get to pick your major in college.
That's it in a nutshell.