Instead, they use a Java 'runtime kernel' that has recently become an extension of the computer operating system, thus the browser only need fuction as a window to multi-tasked processes that are run through the operating system itself. This, supposedly, allows Java to run with greater performance and without being limited to the browser's own memory. A plug-in still is limited to using only as much memory as the browser program itself has been alloted. It also allows Java to be used by more than just the Web browser and Web documents, though so far one would be hard pressed to find any Java software on a personal computer that isn't Web based. Another part of the dialogue between browser and server is the exchange of so-called 'cookies', subject of much controversy when this feature was first brought into use.
Cookies are special information packets sent by a browser in response to a request from aserver.
They contain information like the user ID info put in the browser preferences, the version of the browser software and the kind of computer it runs on, the user's latest browser action, and so on. Because HTTP is a blind anonymous transfer protocol, it did not have any mechanism by which a Web site could recognize who was using it other than by their IP address. For commercial Web sites this was a problem. They wanted to make Web sites seem more personal by having them immediately recognize the user, welcome him by name, and tailor features according to their use habits. In response to this demand Netscape and Microsoft implemented a 'cookie' system which allowed the browser to send packets of information about the browser that could be logged in a site use log file.