Imagine you are a publisher and you have a website where you provide content about microwaves. Based on this information, you gain insights into the types of content that users are reading, and you can use the data to provide personalized content to users. This is called 1st party data because you collected the data and are the only one who has exclusive access to it. With 2nd party data, lets say that you are a business and you sell flights. You sell the data that you've collected about your customers to a company that provides hotel bookings. So, as an airline, you generated 1st party data and sold it to the hotel company, which makes it 2nd party data. Finally comes the 3rd party data. This data is combined from multiple sources of 2nd and 1st party data. It is more general data without detailed customer information. You get information bundles such as "females interested in blue cars". This data is obviously less accurate than 1st and 2nd party data because it is never as specific to your use case needs. Don't confuse the issue of different data models with cookies, they are not always directly linked.