What's the difference between "subsidized" and "unsubsidized" loans?

A subsidized loan does not accrue interest while the student is in school. However the interest on an Unsubsidized Loan is the student’s responsibility and begins to accrue once the loan funds are disbursed. The student can opt to allow the interest to accumulate, however it will be added to the principal amount of the loan and increase the amount to be repaid. It is recommended that the student contact the lender to make quarterly payments on the interest.