This allows for the tracking of your visit and perhaps identifying return visits etc. A shopping cart system needs to keep track of your movements , as apposed to someone else using the same web pages at the same time. This is when sent cookies are most useful in the tracking of current sessions. Also, to avoid the need for repetitive input by visitors returning at a later date, cookies with a longer life span may be implemented, so that previously input information can be displayed automatically. This method is not used where sensitive information is concerned, and no one would want to.
Sensitive information requires the protection of secure password blocks.
Any computer program can be written to scan your computer while it is running, in the background, and store information. If the program is later running while you are on the Web, it is also an easy task for that program to send information with out you knowing. Yet we do not seem to worry about it . This information assists the open design of the Web and cross platform interaction etc. Cookies are 'text only' files .