This is a user agent for Chrome on 64-bit Windows 7, version 90.0.4430.72:
Mozilla / 5.0 (Windows NT 6.1; Win64; X64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/90.0.4430.72 Safari/537.36
In addition to Chrome/90.0.4430.72, there are also Mozilla/5.0, Safari/537.36, AppleWebKit/537.36, etc. Wearing the logo of Mozilla, Safari, etc.? It all started when the browser was born
Mosaic
1993 Mosaic, the first image-enabled browser, was created at the National SuperComputing Center (NCSA) at the University of Illinois.
At this time, the purpose of UA is very simple, just want to tell the server, client browser, operating system type and version
Here is a Mosaic browser UA NCSA_Mosaic/2.0(Windows 3.1)
/ Netscape, Mozilla browser
Marc Andreessen, the brains behind Mosaic, left NCSA and went to Silicon Valley to create a browser called Mozilla.
The Name Mozilla came from Mosaic Killer, which meant to kill Mosaic, and the University of Illinois and the NCSA were not happy about it, so Mozilla was renamed Netscape, which is now known as the Netscape browser
Mozilla’s browser was forced to change its name to Netscape, but its ambition to defeat Mosaic did not change, so Netscape’s user-agent remained Mozilla.
Here is a Netscape browser for UA Mozilla/1.0(Windows 3.1)
So far, UA content has been clean and refreshing
The User Agent sniffer
Different from today, in the early stage of browsers, different browsers have different features. For example, Netscape browsers support the Frames technology. In order to provide better User experience, the server developed the User Agent sniffing function. Support frames Technology Netscape browsers return a page with frames, and other browsers return another page
This technology, which is supposed to improve the user experience by returning different pages to different browsers, has set the stage for UA chaos
Internet Explorer
Netscape’s popularity on the Web threatened Microsoft, then the dominant software company, with its own browser, Internet Explorer, which was free and bundled with Windows as the default browser, Microsoft wants Internet Explorer to be Netscape’s Killer.
IE UA camouflage
When IE was born, it supported the advanced technology of Netscape browser such as Frames, hoping to provide users with a good use experience.
However, the User Agent sniffing of many websites did not adapt to IE and returned pages without frames. This is natural, since Internet Explorer is new, and it will take time for most sites to adapt.
Microsoft can not wait, in order to hit the competitor as soon as possible, made a decision to cause the chaos of UA in the future, UA camouflage
User Agent sniffing on most web sites is not compatible with Internet Explorer, but it is compatible with Netscape.
I don’t know if Netscape sued Microsoft for unfair competition, but this UA disguise made IE a huge success, and other browsers followed suit
Here is an IE UA Mozilla/1.22(compatible; MSIE2.0 Windows 95).
Netscape open source
Through the DISGUISE of UA, IE got the pages with the same advanced features as Netscape, and there was no obvious difference in user experience. In addition, Microsoft’s strategy of bundling and free with Windows defeated Netscape
Eventually Netscape decided to open source the Netscape browser, and the new Mozilla was born, along with a rendering engine called Gecko
In order to demonstrate the power of the Gecko rendering engine and make it easier to adapt to the web server, Mozilla added it to its UA
For example, Mozilla / 5.0 (Windows; U; Windows NT 5.0; en-US; The rv: 1.1) Gecko / 20020826
Gecko
Gecko was a great rendering engine, and many browsers started using it. As Gecko became widely accepted, servers started sniffing Gecko again with User agents
Firefox
Later, Mozilla became Firefox, which added the Firefox logo to the UA to distinguish it from the UA
For example, Mozilla / 5.0 (Windows; U; Windows NT 5.1; sv-SE; The rv: 1.7.5) Gecko / 20041108 Firefox / 1.0
KHTML
Around the same time as Gecko, a rendering engine called KHTML appeared on The Linux platform and was used in Konqueror, also on the Linux platform.
Linux platforms think the KHTML rendering engine is just as good as Gecko. Why not? With Konqueror, set its UA to Mozilla/5.0 (compatible; Konqueror / 3.2; FreeBSD)(KHTML, like Gecko)
KHTML, like Gecko means as good as Gecko
Its and Safari
Apple created a new rendering engine Webkit based on KHTML and used it in its browser Safari. When designing UA, Safari retained the logo of KHTML,like Gecko, and added the logo of AppleWebKit, a new engine
Mozilla / 5.0 (Macintosh; U; PPC Mac OS X; En-us) AppleWebKit/85.7 (KHTML,like Gecko) Safari/85.5
Chrome
Google has developed its own Chrome browser based on the WebKit engine of Safari. For this reason, when designing the UA of Chrome, it is very “kind” to retain all the content of Safari UA, only adding a Chrome logo
For example, at the beginning of this article
Mozilla / 5.0 (Windows NT 6.1; Win64; X64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/90.0.4430.72 Safari/537.36
Edge
Microsoft’s latest Edge browser, based on Chrome’s Chromium core, retains all the content of Chrome UA and adds an Edge logo
Mozilla / 5.0 (Windows NT 10.0; Win64; X64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.114 Safari/ 537.36EDG /91.0.864.54
As a result, the UA of the browser gets longer and more complex
Opera UA toggle
The UAs are getting longer and more complex, but if you want, you can at least distinguish one browser from the other with features. For example, a UA that only contains the Chrome keyword is normally Chrome
But Opera’s move adds another element of uncertainty to the already complex UA.
The Opera browser believes that UA should be left up to the user and has added the ability to switch its UA to another browser’s UA
At this point, the UA has completely deviated from what it was designed to do to help servers distinguish between users’ operating systems and browsers
Current UA Status
After Opera, many browsers support UA toggle function to some extent, such as Chrome debug mode to switch to mobile devices, the UA toggle function, fortunately, most major browsers are relatively limited to UA toggle function! But many niche browsers are different, making them a core selling point, especially on mobile phones
Nowadays, however, there are very few websites that have different Settings for different browsers, and more websites that return different pages according to the OPERATING system (device type and screen size) in UA
The impact of UA disruption on relevant practitioners
There is some influence. It should be noted that UA is no longer the only one to identify the platform where the user resides. Comprehensive discrimination should be combined with other means
The tail
Finally let me shout: Microsoft great crime!!