Data of political campaign contributions made by individual donors is courtesy of Federal Election Commission.
In 1975, Congress created the Federal Election Commission (FEC) to administer and enforce the Federal Election Campaign Act (FECA) - the statute that governs the financing of federal elections. The duties of the FEC, which is an independent regulatory agency, are to disclose campaign finance information, to enforce the provisions of the law such as the limits and prohibitions on contributions, and to oversee the public funding of Presidential elections. See About Federal Election Commission.
Campaign finance refers to all funds raised in order to promote candidates, political parties, or policies in elections, referendums, initiatives, party activities, and party organizations. The funds could also detract from the opponents of the above. Campaign funds is the subject heading under which all books dealing with money in politics are catalogued by the Library of Congress. Other nations use other terms for the subject and offer a broader perspective. Cross-national comparisons prefer the more comprehensive "political finance", researchers in continental Europe use "party finance". All of them deal with "the costs of democracy", a term coined by G. Alexander Heard for his famous analysis of campaign finance in the U.S.
Political campaigns have many expenditures, such as the cost of travel of candidates and staff, political consulting, and/or the direct costs of communicating with voters. The types and purposes of campaign spending depends on the region. For instance, in the United Kingdom, television advertising is provided to campaigning parties for free and limited by law, while in the United States, it is one of the biggest expenses in the campaign budget, especially for statewide and national campaigns. See more detail at Wiki.