Sales of consumer products over the Internet have grown rapidly, including sales of pharmaceutical products. Online pharmacies mimic mail order pharmacies. To operate legally online, pharmacies must be licensed in every state in which sales occur. Although online pharmacies provide benefits to consumers, when compared with traditional pharmacies patients' safety may be compromised. Purchasing prescription drugs online may pose a risk to consumers because they cannot tell whether the site is offering drugs of the same quality offered by a retail pharmacy. There is also a possibility that prescription drugs purchased online may be counterfeit, illegal, or unapproved. A U.S. General Accounting Office study conducted in June 2004 showed that most counterfeit and unapproved drugs sold online are from non-U.S. pharmacies. The Food and Drug Administration and other government agencies have worked to enforce laws on drug sales over the Internet. The biggest challenge in regulating non-U.S. pharmacies is due to their off-shore location. Unfortunately, given the widespread anonymous and ever-changing nature of the Internet, it is very difficult to close down illegal websites.