Recently, one of my friend said he has blocked Trident/4.0 from accessing his websites as he thought its a bot and then his clients complaint that they can’t access their websites. So, I thought I’ll just put some info on it..
Trident (also known as MSHTML) is the name of the layout engine for Internet Explorer. The version that comes with IE 8 is 4.
The User Agent string includes the string ‘Trident/4.0′ in order to allow differentiation between the Internet Explorer 7 User Agent String and the Internet Explorer 8 User Agent string when running in Internet Explorer 7 Compatibility View.
All applications which display content based on a markup language use a layout engine. Gecko is the layout engine for Firefox, Camino, Netscape while WebKit is used in Safari & Chrome