Legally speaking, a third party is a person or group who is not a party to a legal contract or transaction, but who has an interest or involvement in some way. Different areas of law may regard a third party differently, but generally speaking, the third party has no legal rights in the matter at hand, unless they are what is called a third party beneficiary. A third party may be a witness to a transaction or contract and may even have certain legal obligations, but does not have a legal right in the transaction. For example, if a buyer and seller enter into a contract to exchange property, a signed witness to the contract would be a third party who witnessed the legal transaction, but who has no rights in the property exchanged.

In the case of a third party beneficiary, the third party does have some legal rights. An example of this is a parent or grandparent purchasing a vehicle or house to be given to a child or grandchild. The child or grandchild becomes the third party beneficiary, and as such, has legal rights in the transaction. If the seller fails to deliver the property after the transaction, the intended recipient may take legal action.

Though a third party in legal matters may or may not have legal rights, he or she may have legal obligations. For example, a third party witness in a crime or accident may be required to appear in court. Though he or she may have no involvement with the crime or accident, a third party who witnesses either is obligated to follow court mandates in any proceedings regarding the matter.

The concept of a third party relates not only to law, but also to politics and manufacturing. In politics, a third party is any other political party in a democratic system besides the predominant two. In America, the Independent party is considered a third party, with the Democratic and Republican parties being the primary two. In manufacturing, third party generally refers to a product’s after-market additions or an enhancement made after the original manufacturing process.