Definition - What does Lurker mean?
A lurker is an Internet user who, rather than participating in interactive websites such as social media platforms, only passively observes information and does not reveal information about himself or herself. These passive users may view text and images, download information, visit other people's profiles or request information through the Internet, but do not post, update their profiles, share links, use social media indicators or otherwise create an online or social media footprint.
Techopedia explains Lurker
The idea of looking at "lurking" online behavior is central to all sorts of social media analysis, online marketing, research on the psychology of Web users, and other aspects of evaluating the Internet and how people use it in their lives. Lurking is essentially a big question mark in Web use — it makes the individual a lot more difficult to trace through his or her Web footprint, while allowing that person to still acquire a lot of information through various Web sources.
In terms of Web lurking and data acquisition, it is important to note that while lurking reveals a lot less about a personal on social media, marketers may still be able to collect a large amount of information about that person. For example, even when someone visits a website and doesn't buy products or services, or when they passively review social media sites, different types of cookies, beacons and other marketing tools can acquire information about that person, including items like their search or purchase history, IP address, demographics and more.