A third-party source is independent of the first party and second party in a transaction, interview, or written description (etc.). A first-party source comes directly from the first party (such as a self-published document or product description). A second-party source is controlled by the second party, such as a customer who has written some product requirements, or a prior book or article written by the same author.

In commerce

Commerce

While business refers to the value-creating activities of an organization for profit, commerce means the whole system of an economy that constitutes an environment for business. The system includes legal, economic, political, social, cultural, and technological systems that are in operation in any...

, a "third-party source" means a supplier

Supplier

Supplier may refer to:*Manufacturer, uses tools and labor to make things for sale*Processor , converts a product from one form to another*Packager , encloses products for distribution, storage, sale, and use...

 (or service provider

Service provider

A service provider is an entity that provides services to other entities. Usually, this refers to a business that provides subscription or web service to other businesses or individuals. Examples of these services include Internet access, Mobile phone operators, and web application hosting...

) who is not directly controlled by either the seller (first party) or the customer

Customer

A customer is usually used to refer to a current or potential buyer or user of the products of an individual or organization, called the supplier, seller, or vendor. This is typically through purchasing or renting goods or services...

/buyer

Buyer

When someone gets characterised by their role as buyer of certain assets, the term "buyer" gets new meaning:A "buyer" or merchandiser is a person who purchases finished goods, typically for resale, for a firm, government, or organization...

 (second party) in a business transaction

Financial transaction

A financial transaction is an event or condition under the contract between a buyer and a seller to exchange an asset for payment. It involves a change in the status of the finances of two or more businesses or individuals.-History:...

. The third party is considered independent from the other two, even if hired by them, because not all control is vested in that connection. There can be multiple third-party sources with respect to a given transaction, between the first and second parties. A second-party source would be under direct control of the second party in the transaction.

In journalism

Journalism

Journalism is the practice of investigation and reporting of events, issues and trends to a broad audience in a timely fashion. Though there are many variations of journalism, the ideal is to inform the intended audience. Along with covering organizations and institutions such as government and...

, a "third-party source" is a document or entity which is not directly controlled by either the subject (first party) or the author (second party) of a written text. For example, a third-party source might be a prior news report about the primary subject (first party) of the writing. A second-party source could be a previous article already written by the same author (the second party) or by a group under direct control of that author. A first-party source might be an autobiography

Autobiography

An autobiography is a book about the life of a person, written by that person.-Origin of the term:...

 or product description written by the subject.

In Information Technology

Information technology

Information technology is the acquisition, processing, storage and dissemination of vocal, pictorial, textual and numerical information by a microelectronics-based combination of computing and telecommunications...

, a "third-party source" is a supplier of software (or a computer accessory) which is independent of the supplier and customer of the major computer product(s).

There are other uses of the term "third-party source" as well.