I wish to know all the pros and cons about using these two methods. In particular the implications on web security.
Thanks.
If you are passing things like passwords or other sensitive information, always use POST and make sure you are using SSL so that data doesn't travel between the client and server in clear-text.
Security-wise, the downside of using GET is that all the submitted data will be in the URL, and therefore stored locally on the client in the browser history.