No Party Affiliation or NPA is a term used to apply to those voters or politicians who do not hold an affiliation with any particular political party. Another term which is often used in place of "NPA" is "Independent".
In the U.S. state of Michigan for example, the term "Independent" is not used by the Secretary of State of Michigan because it could be interpreted as a party affiliation. Likewise, when Ross Perot's Reform Party initially organized as the "Independence Party", the name was rejected because the Secretary of State decided that the name would be misleading to voters who may mistake it for the concept of "No Party Affiliation". This was one of the reasons that the name of the party changed to the "Reform Party". In California the label "Independent" applies to the American Independent Party, founded by George Wallace, and currently affiliated with the U.S. Constitution Party.