Exactly what is a "third party"? (And who are the first and second party?)

I know precisely what a "third-party library" is, so I assume that the "third-party" in this case, simply is an arbitrary person/company other than the developer?

Has it to do with "first person" / "second person" etc perhaps?

The fact that there is a "third party" suggests that there is a "first party" and a "second party" as well. Are those terms well defined?

(I'm not a native english speaker.)

If you are developing software for a client, then there is a contract between you/your company, and the client/their company. These are the two parties to the contract. Anyone else, not bound by the contract, is a third party. It's used wherever a contract exists between two parties to mean anyone not bound by the contract.

There is no fixed meaning to which of the two parties is 'first' and which 'second', usually you will think you're the first party, and the client the second, whereas the client will think they are the first party and you the second, in a similar fashion to first, second and third person I/he/they.

These terms are well defined in English when talking about grammar (English grammar or another language's).

• First person corresponds to the pronouns "I" and "we"; "me" and "us" (so a book written in the first person is a story told by the central character - "I did this" as opposed to "Smith did this").

• Second person corresponds to the pronoun "you".

• Third person corresponds to the pronouns" he", "she", "it" and "they"; "him", "her" and "them".

So "third party" just means not you or me, but them.

1st party = I

2nd party = you

3rd party = he/she (i.e. someone external to the conversation)

Let's take Iphone for example. Apple by its hardware and software are first party. End user like me and you are the second party . the third party is the person who enter this relation like an app developer that effect me and apple .

Note: the first and second party can be swapped .

• First party: developers
• Second party: end users (I think)
• Third party: Libraries etc provided by someone else other than the developers. PDFSharp will be considered 3rd party.

I don't think first and second party are used that much, if at all, in programming. If someone started talking about first and second parties at work, I would wonder what they meant. However, "third party" is much more common and familiar.

"Third party software" is a common term. I've never heard of "first party software", or "second party software".

PS: I'm a native English speaker in the UK.

It's a term that's often used in Windows-centric development: the first and second parties are me (or you), and Microsoft; and the third party is anyone else:

• Sometimes it means the customer or end user (e.g. "if we get a 'redistributable' from Microsoft, that means that we can redistribute it to 'third parties'")

• More often, it means a non-Microsoft vendor of programming tools or libraries, which I'm using (for example, "NUnit and Reflector are both example of 'third-party' tools").

It is related to the ISO/IEC 17024 Conformity Assessment.

1st party:

• Is performed by the person or organization that provides the object

2nd party:

• Is performed by a person or organization that has a user interest in the object

3rd party:

• Is performed by a person or body that is independent of the person or organization that provides the object, and of the user interests in that object

---

Conclusion:

• First party is the person self-attesting that he or she is competent.
• Second party is someone related to the person (trainer/instructor/employer) declaring that the person is competent.
• Third party would require an entirely independent party to declare the person competent.

My Source: http://www.proftesting.com/blog/2016/09/28/first-second-and-third-party/

Oxford Dictionnary

third party
noun
a person or group besides the two primarily involved in a situation, esp. a dispute.
• a political party organized as an alternative to the major parties in a two-party system. adjective [attrib.]
of or relating to a person or group besides the two primarily involved in a situation : third-party suppliers.

I think of it as from where the code comes from, so when it comes to libraries and development tools I'd say that the first and second parties are the developer and the producer of the development tool. So as a .Net developer the parties are me and Microsoft, since I write code using Microsofts framework and controls and I might also then user third party code/controls.

1st party is Developer, 2nd party is software user

It's context driven though. This situation also applies. From a development perspective: I'm developing an app for my company for internal use (first Party) Most of the "assets" that I'm using for the app are from Microsoft (second party) But I'm also using this database library from this other company (third party)

First and Second remain interchangeable depending on perspective. The customer isn't even on this chart but that's partially because that's an entirely different relationship with it's own rules.

Be careful when talking about legal contracts because while they do often use the term third party as we're discussing, there is also the practice of identifying pe4ople as"the party of the first part A, the party of the second part B, the party of the Third part C, ... , the party of the nth part ...

which serves only to list a bunch of people without specifying a relationship. And it can also be the parties of the first part a,b,c and the parties of the second part x,y,z, ...

The first party is the developer of the website, program, or game. Like Microsoft or Google.

The second party is the client, the viewer of the developer's work.

The third party is an external source of media.