Cross-site scripting (XSS) is a type of computer security vulnerability typically found in web applications that enables malicious attackers to inject client-side script into web pages viewed by other users.Last week twitter was influenced by this kind of attack and two days back same happened with orkut,now if you are thinking that you dont use these sites let me inform you that it can be used on any site having a vulnerability so shouldnt you be protective at your side incase you want to know more about XSS known as Cross Site Scripting you can refer to wikipedia or google it for more
To protect you from such kind of attacks you can use an addon NoScript for mozilla firefox which is no doubt the best internet browser if still you are not on mozilla you can install it from here
http://www.mozilla.com/en-US/firefox
after installing it you can install NoScript from here
https://addons.mozilla.org/en-US/firefox/addon/722/
And see yourself the number of downloads it also helps in blocking any malicious script and depending upon the site`s authenticity you can allow or block it
