data platform (CDP), customer relationship management (CRM) or data management platform (DMP) to enrich users' profiles with external data. It is possible to expand the knowledge about existing users by using external sources. Data streams are used to enrich business intelligence systems and make analysis more precise and conclusions more accurate. In the case of content management system (CMS) integration, Data Stream is used to identify the users and personalize their visit, even if it's their first one. By data analysis, the actual content of the website is adapted to the user. Data streams are integrated with demand side platform (DSP) within programmatic advertising ecosystem. Parties (e.g., advertisers) can exchange the users' IDs and concatenate with them existing profiles. Data streams are used to choose respective user segments (e.g., people interested in the automotive industry) and use them in an online campaign. Segments are enriched with more user characteristics out of data stream and then sent to DSP. Data sources visible In a data stream it is visible what device has been used by the user side – it is visible on user agent: mobile – when a user uses a mobile browser to explore, it has narrow screen resolution and mobile app version, respectively; desktop – when a user uses a desktop browser or app version. The following information is shared out of used device: Actual URL to the visited website, where an event occurred User Agent Geolocation Internet Protocol (IP) Formats A data point is a tag that collects information about a certain action, performed by a user on a website. Data points exists in two types, the values of which are used to create appropriate audiences. Those are: 'event' with information about occurrences of the specific event (e.g., click on a link or displaying ad) 'attribute' with numerical or alphanumerical values. Segment is a logical statement, built on specific Data Points using AND, OR or NOT operators. Hybrid data – raw data out of both Data Point and Segment data formats. URLs – is a set of information about a particular URL that has been visited. GDPR Information gathered out of websites are based on user behavior. Data providers deliver both personal or non-personal information. There are two types of user data available in data stream: Personally identifiable information (PII) – information that allows clearly or by combining with data identification methods identify a person. Examples of