Though they're great, subsidized loans have a limit to how much you can borrow. This limit increases every year you're in school, but it's still a pretty low amount, especially for private school tuition. In the experience with my children, they have not received enough money in subsidized loans to cover everything. We've had to seek outside sources for each of them, which means interest accrued on some of their loans.

Pretty much all student loans allow you to defer payment until after the student has graduated. Student loans through a bank or school will almost always accrue interest while the student is in school, even though you're not making any payments on them. Only loans subsidized by the government have no interest accrue until after the student graduates.

There are student loans subsidized by the government, and loans unsubsidized by the government. Subsidized loans include the Federal Stafford loans, fairly widely available, and the Federal Perkins loans, reserved for the most in need. The government will pay the interest on these loans while the student is a "full-time student," which has varying definitions depending on what school you're talking about. Unsubsidized loans will accrue interest while the student is in school, but you won't have to start paying them back until after graduation.