It is important for you to update your browser when updates become available as this helps to prevent hackers from taking advantage of any vulnerabilities older version may pose. In addition, online transactions that involve sensitive data such as credit card information require that the your browser meet the minimum requirements and support encryption 128-bit SSL sessions.
Internet cookies are small pieces of data which are used to help websites identify their users when they visit their site. An example of how a cookie is used is when your username is already filled in the login form.
Java applets are small applications that run within a browser that are embedded within a web page as opposed to being stand alone applications. Java applets are typically used when the program is too large to be included in the web page or if the author does not want their code to be visible to others. Java applets can be used to run animation/graphics, chat rooms, calculators and various other tasks. In order to use Java applets you have to install a Java plug-in which can be downloaded from Sun Microsystems