It is encrypted information about your identity and recent browsing. In Internet Explorer you can simply delete the file that represents the cookie. For Netscape Communicator it is not so simple. However, you will also reset all browser options to the original configuration, and nothing will appear in your history. Another bit of information contained in the cookie is its lifetime.
All cookies contain an expiration date.
The next time you close your browser, the cookie will be deleted from your hard drive. Some browser software maintains the new cookie data in memory and does not write it to the hard drive until you close the browser program. If the expiration date has passed, it is never written to the hard drive. SSL is a means to encrypt all data exchanged in a browsing session. So a server can indicate in the cookie that it will only transmit over an encrypted connection, or not make this distinction.