Medary.com

It's pretty simple to understand, really. This definition of political corruption comes from the Wikipedia article:

"Political corruption is the use of legislated powers by government officials for illegitimate private gain."

My only quibble with that definition is the inclusion of the word "legislated" in the definition. I suppose that the author is saying that corruption only includes the use of "legitimate" government power for private gain. But then, if it's used for private gain, wouldn't that use of government power be by definition illegitimate?

More after the "read more." The Wikipedia article goes on to discuss eight different types of political corruption:

Bribery

Bribery requires two participants: one to give the bribe, and one to take it. In some countries the culture of corruption extends to every aspect of public life, making it extremely difficult for individuals to stay in business without resorting to bribes. Bribes may be demanded in order for an official to do something he is already paid to do. They may also be demanded in order to bypass laws and regulations. In some developing nations, up to half of the population has paid bribes during the past 12 months.

Graft

While bribery includes an intent to influence or be influenced by another for personal gain, which is often difficult to prove, graft only requires that the official gains something of value, not part of his official pay, when doing his work. Large "gifts" qualify as graft, and most countries have laws against it. (For example, any gift over $200 value made to the President of the United States is considered to be a gift to the Office of the Presidency and not to the President himself. The outgoing President must buy it if he or she wants to keep it.) Another example of graft is a politician using his knowledge of zoning to purchase land which he knows is planned for development, before this is publicly known, and then selling it at a significant profit. This is comparable to insider trading in business.

Patronage

Patronage refers to favoring supporters, for example with government employment. This may be legitimate, as when a newly elected government changes the top officials in the administration in order to effectively implement its policy. It can be seen as corruption if this means that incompetent persons, as a payment for supporting the regime, are selected before more able ones. In nondemocracies many government officials are often selected for loyalty rather than ability. They may be almost exclusively selected from a particular group (for example, Sunni Arabs in Saddam Hussein's Iraq, the nomenklatura in the Soviet Union, or the Junkers in Imperial Germany) that support the regime in return for such favors.

Nepotism and Cronyism

Favoring relatives (nepotism) or personal friends (cronyism) of an official is a form of illegitimate private gain. This may be combined with bribery, for example demanding that a business should employ a relative of an official controlling regulations affecting the business. The most extreme example is when the entire state is inherited, as in North Korea or Syria. A milder form of cronyism is an "old boy network", in which appointees to official positions are selected only from a closed and exclusive social network – such as the alumni of particular universities – instead of appointing the most competent candidate.

Seeking to harm enemies becomes corruption when official powers are illegitimately used as means to this end. For example, trumped-up charges are often brought up against journalists or writers who bring up politically sensitive issues, such as a politician's acceptance of bribes.

Embezzlement

Embezzlement is outright theft of entrusted funds. It is a misappropriation of property.

Another common type of embezzlement is that of entrusted government resources; for example, when a director of a public enterprise employs company workers to build or renovate his own house.

Kickbacks

A kickback is an official's share of misappropriated funds allocated from his or her organization to an organization involved in corrupt bidding. For example, suppose that a politician is in charge of choosing how to spend some public funds. He can give a contract to a company that is not the best bidder, or allocate more than they deserve. In this case, the company benefits, and in exchange for betraying the public, the official receives a kickback payment, which is a portion of the sum the company received. This sum itself may be all or a portion of the difference between the actual (inflated) payment to the company and the (lower) market-based price that would have been paid had the bidding been competitive. Kickbacks are not limited to government officials; any situation in which people are entrusted to spend funds that do not belong to them are susceptible to this kind of corruption.

Unholy alliance

An unholy alliance is a coalition among seemingly antagonistic groups, especially if one is religious, for ad hoc or hidden gain. Like patronage, unholy alliances are not necessarily illegal, but unlike patronage, by its deceptive nature and often great financial resources, an unholy alliance can be much more dangerous to the public interest. An early, well-known use of the term was by Theodore Roosevelt (TR):

"To destroy this invisible Government, to dissolve the unholy alliance between corrupt business and corrupt politics is the first task of the statesmanship of the day." – 1912 Progressive Party Platform, attributed to TR and quoted again in his autobiography where he connects trusts and monopolies (sugar interests, Standard Oil, etc.) to Woodrow Wilson, Howard Taft, and consequently both major political parties.

Involvement in organized crime

An illustrative example of official involvement in organized crime can be found from 1920s and 1930s Shanghai, where Huang Jinrong was a police chief in the French concession, while simultaneously being a gang boss and co-operating with Du Yuesheng, the local gang ringleader. The relationship kept the flow of profits from the gang's gambling dens, prostitution, and protection rackets undisturbed.

The United States accused Manuel Noriega's government in Panama of being a "narcokleptocracy", a corrupt government profiting on illegal drug trade. Later the U.S. invaded Panama and captured Noriega.