Final answer:
Small data files stored on user's hard disk when visiting websites are called cookies, which are a privacy risk due to their ability to track online activities, raising concerns about online privacy.
Step-by-step explanation:
Small data files that are deposited on a user's hard disk when they visit a website are called cookies. Cookies themselves are simply files that can store information such as user preferences and browsing habits, which help in making the user experience more personalized and efficient. However, these files become a potential privacy risk because they can contain detailed records of one's online activities. This has become a great concern for many as the Pew Research Center reports an increase in Internet users concerned about the amount of personal information available online.
The risk becomes even more pronounced considering that hackers have various methods like phishing to breach data or lure individuals into compromising their online privacy. This highlights the need for robust cyber data privacy laws, such as the Children's Online Privacy Protection Act (COPPA) and stringent cybersecurity measures for individuals and businesses alike.