Why are web browser cookies considered potentially dangerous?

Web browser cookies are considered potentially dangerous primarily because they support identification and tracking of users. Cookies store user-specific information such as preferences, login credentials, and activity across different web sessions. While this functionality enhances user experience by allowing websites to remember users and personalize content, it also raises privacy concerns. Advertisers and third-party entities can use cookies to track user behavior across various websites, creating detailed profiles without the user's explicit consent. This tracking can lead to unauthorized data collection and can compromise individuals' privacy, which is why this aspect of cookies is regarded as a potential threat.

Other options discuss unrelated issues. While cookies may have an effect on browser performance if not managed well, that is not a primary concern. The potential for cookies being hacked is limited and highly dependent on other security measures in place; therefore, it's not considered a main issue. Although cookies consume some disk space, this is typically not significant enough to be a primary danger compared to privacy implications.