WOT (Web of trust) is a community based website reputation system. It can be installed on various browser such as Firefox, Google Chrome and others. It provides community based rating for search results and sites.
WOT is not a unique program but It is widely used and have ability to show right information. This is all because of its popularity. There are a lot of antivirus program that comes with similar program but fails to satisfy, atleast me.
This is a small add-on which has also negligible impact on your browser speed and surfing experience. Hence if you are using a dialup connection or old computer, you may also install and enjoy this.
Since rating depends upon the data obtained by its user, so it can be easily manipulated, So one should not rely on this and provide any personal information to less popular sites. The information obtained from here should be used to make a rough idea only.