As part of the Treasury Department of the United States government, the Secret Service is often associated with providing protection to current and past presidents, as well as members of the immediate families of the incumbent president or past presidents. Along with providing protection to key government officials and their families, the Secret Service also is often called upon to provide protective services to visiting heads of state, the candidates in upcoming presidential elections, and other protective assignments as needed. The Secret Service also plays a vital role in the task of limiting the operation of counterfeiting operations within the country as well.

The origins of the Secret Service can be traced back to the period just after the American Civil War. At the time, a large proportion of currency that was in circulation throughout the nation was in fact counterfeit. On 5 July 1865, the Secret Service was created under the auspices of the Department of the Treasury and charged with the task of eliminating the vast proliferation of counterfeiting operations within the country. By the middle of the 1870s, the United States Secret Service had greatly reduced the production of counterfeit currency within the nation, as well as creating a framework that helped to contain the threat of counterfeiting from undermining the economy.

After the assassination of President William McKinley in 1901, public outcry demanded that the government take steps to protect the lives of anyone current filling the office or president. Congress made the Secret Service responsible for carrying out this task in 1906. Over time, the protection offered by the Service was extended to family members and other persons important to the function of the government. With these new duties, the ability of the Secret Service to interact with, and function within the jurisdictions of state and local law enforcement was greatly expanded.

At various times throughout the 20th century, the Secret Service has been called upon to assign secret agents to provide protection for important documents, visiting heads of state, and important works of art that are brought into the United States for public exhibition. Training as a secret agent with the Secret Service is among the most intense and comprehensive training programs in existence, with only a small portion of applicants being accepted into the program and even fewer persons completing the training.

The authority of the Secret Service in regard to financial matters in the United States has also expanded over the years. Toward the end of the 20th century, the Secret Service was granted additional powers to investigate matters involving cases of false identity, credit fraud, and fraud involving the use of bank debit cards. The Secret Service was also granted authority to investigate issues surrounding all federally insured financial institutions, including savings and loans operations.

Today, the Secret Service maintains a presence in a number of locations around the United States, as well as a range of liaison offices at international locations. Among some of the international sites of Secret Service facilities are such noted cities as Paris, London, Rome, and Bangkok. With close to five thousand employees, the agency is composed of a pool of highly trained experts in such diverse fields as psychology, forensics, security, electronic engineering, and communications.