What are cookies? What's the use?

A hot topic recently, is cookie safe? 3. After the15 party, many netizens were worried about the privacy of cookies. Let's take a closer look at cookies and authoritative views. Cookies are a technology that allows the website server to store a small amount of data in the client's hard disk or memory, or read data from the client's hard disk. Cookies are very small text files that are put on your hard disk by the Web server when you browse a website. It can record your user ID, password, the pages you visited, the time you stayed and other information. When you come to the website again, the website can read Cookies and get your relevant information, so you can take corresponding actions, such as displaying a welcome slogan on the page, or allowing you to log in directly without entering an ID or password. It can be regarded as your ID card in essence. But Cookies cannot be executed as code, nor can they spread viruses, and they are exclusive to you and can only be read by the server that provides them. The saved pieces of information are stored in the form of name-value pairs, which are just a named piece of data. A website can only get the information it puts on your computer, it can't get the information from other Cookies, and it can't get anything else on your computer. Most of the contents in Cookies are encrypted, so the average user seems to be just meaningless alphanumeric combinations, and only the CGI processor of the server knows their true meaning. Cookies are text files or data stored in the hard disk of the user's computer transmitted by the website we visit, so their storage location in the hard disk is closely related to the operating system and browser used. In fact, personal sensitive information such as user name and password stored in Cookie are usually encrypted, which is difficult to reverse crack. But this does not mean absolute safety. Hackers can steal cookies from users' browsers through Trojan virus, and directly cheat websites by stealing cookies. It can be seen that Trojan horse virus invading users' computers is a major culprit leading to the disclosure of users' personal information. Since the birth of 1993 Cookie, it has the principle of exclusivity, that is, the user information stored in the Cookie by website A is not directly obtained by website B, but now some third-party advertising alliance codes are widely used. This leads users to search for a keyword on website A, and users continue to visit website B. Because website B also uses the same third-party advertising code, this code can obtain users' search behavior on website A from Cookie, and then show more accurate promotional advertisements. For example, search for keywords such as diabetes, and then visit its alliance website, and advertisements for diabetes treatment will immediately appear on the page. If you don't inform in advance and get the user's consent, this practice is suspected of violating privacy. At present, this is still in a gray area. Therefore, cross-site cookies are the chief culprit of users' privacy leakage, so it is urgent to restrict websites from using cross-site cookies and provide users with DNT function options. It is understood that at present, browsers such as IE, Chrome, 360 and sogou can quickly delete Cookie information from users' web pages. However, from the current overall privacy protection environment, there is still a huge protection gap in security software.