A private student loan is a financing option for higher education in the United States that can supplement, but should not replace, federal loans, such as Stafford loans, Perkins loans and PLUS loans. Private loans, which are heavily advertised, do not have the forbearance and deferral options available with federal loans (which are never advertised). In contrast with federal subsidized loans, interest accrues while the student is in college, even if repayment does not begin until after graduation. While unsubsidized federal loans do have interest charges while the student is studying, private student loan rates are usually higher, sometimes much higher. Fees vary greatly, and legal cases have reported collection charges reaching 50% of amount of the loan. Since 2011, most private student loans are offered with zero fees, effectively rolling the fees into the interest rates. Interest rates and loan terms are set by the financial institution that underwrites the loan, typically based on the perceived risk that the borrower may be delinquent or in default of payments of the loan. Most lenders assign interest rates based on 4-6 tiers of credit scores. The underwriting decision is complicated by the fact that students often do not have a credit history that would indicate creditworthiness. As a result, interest rates may vary considerably across lenders, and some loans have variable interest rates. More than 90% of private student loans to undergraduate students and more than 75% of private student loans to graduate students require a creditworthy cosigner. Unlike other consumer loans, Congress made student loans, both federal and private, exempt from discharge (cancellation) in the event of a personal bankruptcy, except when repaying the student loan would represent an undue hardship on the borrower and the borrower's dependents. This is a serious restriction that students rarely understand when obtaining a student loan. Financial aid, including loans, may not exceed the college's cost of attendance. Parallels to mortgage lending The increase in use of private student loans came about around 2001 once the increase in the cost of education began to exceed the increase in the amount of federal student aid available. The recent history of student loans has been compared to the history of the mortgage industry. Similar to the way in which mortgages were securitized and sold off by lenders to investors, student loans were also sold off to investors, thereby eliminating the risk of loss for the actual