Contributor Agreement defines the terms under which intellectual property has been contributed to a company/project, typically software under an open source license or the education content.
Contributor Agreements can be used to enable vendors to easily pursue legal resolution in the case of copyright disputes, or to relicense products to which contributions have been received from third parties. Contributor Agreements are important especially for corporate open source projects under a copyleft license, since without a Contributor Agreement the contribution would restrict the guardian as well.
The purpose of a Contributor Agreement is to ensure that the guardian of a project's outputs has the necessary ownership or grants of rights over all contributions to allow them to distribute under the chosen license. In some cases this will mean that the contributor will assign the copyright in all contributions to the project owner; in other cases, they will grant an irrevocable license to allow the project maintainer to use the contribution. Contributor Agreements also have roles in raising awareness of IPR issues within a project.