Question

Why does Internet Explorer has Mozilla in UserAgent?

In Firefox it’s stating:

Mozilla/5.0 (Windows NT 6.1; rv:7.0.1) Gecko/20100101 Firefox/7.0.1

In Interner Explorer it’s stating:

Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Trident/5.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; Tablet PC 2.0; .NET4.0E; .NET4.0C)

In some blogs/forums it’s mentioned, that it is due to some historical reasons, but what’s the reason?

It would be very helpful to know about it.

Answer 1

this should do it:

http://en.wikipedia.org/wiki/Mozilla

When users visit a website (via a user agent such as a web browser), a
text string is generally sent to identify the user agent to the web
server. It is known as the “user agent string”. The Netscape web
browser identified itself as “Mozilla/” followed by some
information about the operating system it was running on.

Because the Netscape browser initially implemented many features not
available in other browsers and quickly came to dominate the market, a
number of web sites were designed to work, or work fully, only when
they detected an appropriate version of Mozilla in the user agent
string. Thus, competing browsers began to emulate (“cloak” or “spoof”)
this string in order to also work with those sites. The earliest
example of this is Internet Explorer’s use of a user agent string
beginning “Mozilla/ (compatible; MSIE …”, in order
to receive content intended for Netscape, its main rival at the time
of its development. This format of user agent string has since been
copied by other user agents, and persisted even after Internet
Explorer came to dominate the browser market.

wiki knows everything

also https://superuser.com/questions/113020/why-does-internet-explorer-calls-itself-mozilla