First party data refers to data that is collected by a website or app from its own users, typically through the use of cookies or other tracking technologies. First party data is owned by the website or app, and can be used for a variety of purposes, such as personalization, analysis, or advertising. First party data is often considered to be more valuable and reliable than third party data, as it is collected directly from the source and is specific to the website or app. However, first party data can also be subject to privacy concerns, and may require the consent of users in order to be collected and used.