A union in the commercial sense is a group of people united for a common purpose related to business or livelihood.

Examples include:

• labor unions
• credit union
  Credit union
  A credit union is a cooperative financial institution that is owned and controlled by its members and operated for the purpose of promoting thrift, providing credit at competitive rates, and providing other financial services to its members...
  
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Labor unions may or may not be recognized in law, and their officers or other leaders may or may not be chosen in a democratic fashion. Credit unions are normally recognized in law; if not, they may be more properly termed "credit associations" or "self-help associations."