An independent, non-partisan politician or non-affiliated politician is a politician not affiliated with any political party or bureaucratic association. There are numerous reasons why someone may stand for office as an independent.
Marshal Mannerheim, the 6th President of Finland
A political party is an organization that coordinates candidates to compete in a particular country's elections. It is common for the members of a party to hold similar ideas about politics, and parties may promote specific ideological or policy goals.
The members of political parties, such as those of the Indian National Congress (pictured), coordinate to collectively achieve and use political power.
In A Block for the Wigs (1783), James Gillray caricatured Fox's return to power in a coalition with North. George III is the blockhead in the centre.
Political parties like the Romanian Communist Party can arise out of, or be closely connected to, existing segments of society, such as organizations of workers.
It is easier for voters to evaluate one simple list of policies for each party, like this platform for the United Australia Party, than to individually judge every single candidate.