A president is a leader of an organization, company, club, trade union, university, or country.

Etymologically, a president is one who presides, who sits in leadership (from Latin pre- "before" + sedere "to sit"; giving the term praeses). Originally, the term referred to the presiding officer of a ceremony or meeting (i.e., chairman), but today it most commonly refers to an official. Among other things, "President" today is a common title for the heads of state of most republics, whether popularly elected, chosen by the legislature or by a special electoral college.

Presidents in countries with a democratic or representative form of government are usually elected for a specified period of time and in some cases may be re-elected by the same process by which they are appointed, i.e. in many nations, periodic popular elections. The powers vested in such presidents vary considerably. Some presidencies, such as that of Ireland, are largely ceremonial, whereas other systems vest the President with substantive powers such as the appointment and dismissal of Prime Ministers or cabinets, the power to declare war, and powers of veto on legislation. In many nations the President is also the Commander-in-Chief of the nation's armed forces, though once again this can range from a ceremonial role to one with considerable authority.

Jill Stein (born 1950) is an American physician and candidate for President of the United States in 2012 with the Green Party of the United States. Stein was a candidate for Governor of Massachusetts in the 2002 and the 2010 gubernatorial elections. Stein is a resident of Lexington, Massachusetts and a 1979 graduate of Harvard Medical School. She serves on the boards of Greater Boston Physicians for Social Responsibility and MassVoters for Fair Elections, and has been active with the Massachusetts Coalition for Healthy Communities.

In October 2011, Stein announced her candidacy for the presidential nomination of the Green Party in the 2012 general election.

Stein advocates for the creation of a "Green New Deal", the objective of which would be to employ "every American willing and able to work" to address "climate change...[and the] converging water, soil, fisheries, forest, and fossil fuel crises" by working towards "sustainable energy, transportation and production infrastructure: clean renewable energy generation, energy efficiency, intra-city mass transit and inter-city railroads, “complete streets” that safely encourage bike and pedestrian traffic, regional food systems based on sustainable organic agriculture, and clean manufacturing of the goods needed to support this sustainable economy". The initial cost of the Green New Deal would be funded by various mechanisms, including "taxing Wall Street speculation, off shore tax havens, millionaires and multimillion dollar estates" as well as a 30% reduction in the U.S. military budget. She cites a study of the economic effects of the 1930s New Deal projects by Dr. Phillip Harvey, Professor of Law & Economics at Rutgers School of Law as academic evidence for the Green New Deal.