Trident (layout engine)

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Trident (also known as MSHTML) is the name of the layout engine for the Microsoft Windows version of Internet Explorer. It was first introduced with the release of Internet Explorer version 4 in October 1997, has been steadily upgraded and remains in use today. For version 7 of Internet Explorer, Microsoft made significant changes to the Trident layout engine to improve compliance with web standards and add support for new technologies. Despite these changes, Trident remains significantly less compliant than competing layout engines Gecko, Presto and WebCore.^[1]

Trident was designed as a software component to allow software developers to easily add web browsing functionality to their own applications. It presents a COM interface for accessing and editing web pages in any COM-supported environment, like C++ and .NET. For instance, a web browser control can be added to a C++ program and Trident can then be used to access the page currently displayed in the web browser and retrieve element values. Events from the web browser control can also be captured. Trident functionality becomes available by connecting the file mshtml.dll to the software project.

Alternatively, Microsoft also has several other layout engines. One of them, known as Tasman, was used in Internet Explorer for Mac. Tasman is known for its better standards support. Contrary to popular belief, although development of Internet Explorer for Mac has halted, development of Tasman continues, with its most recent release as part of Office 2004 for Mac. The applications in Microsoft Office 2007 for Windows (Word, Outlook etc) use their own HTML editing/rendering engine which is worse at supporting web standards. Also, Microsoft's new web design product, Expression Web, again does not use Internet Explorer's Trident engine, but rather its own engine which Microsoft claims is the most standards-compliant on the market today. ^[2]

1 Versions
2 Trident-based applications
3 See also
4 References

[edit] Versions

Trident (IE4)
Trident II (IE5) (improved CSS1.0 support and had sweeping changes in CSS2 rendering)
Trident III (IE5.5) (corrected issues with CSS handling)
Trident IV (IE6) (corrected the box model and added quirks mode with DTD switching)
Trident V (IE7) (fixes many CSS rendering issues and adds partial PNG alpha support)

[edit] Trident-based applications

All versions of Internet Explorer for Windows from 4.0 onwards use Trident, and it is also used by various other web browsers and software components (see Internet Explorer shells). In Windows 98, Windows Me, and Windows 2000, it is also used for the Windows file manager / shell, Windows Explorer. In Windows XP and newer versions, the DirectUI engine is used instead.^[3]

Some other Trident-based applications include:

EA Downloader, incompatible with Trident V as of Internet Explorer 7 RC2
Google Talk, which uses Trident to render chat windows and profile cards
Microsoft Office InfoPath
Microsoft Encarta and related products
Microsoft Office Outlook and Outlook Express, which use Trident to render HTML Messages and the "Outlook Today" screen
MSN Messenger, which uses it to produce flash-based "winks" and games, and for all advertisements shown in the advertisement banner
Netscape Browser, which uses Trident to render web pages in IE mode
RealArcade
TomeRaider
Valve's Steam software, which uses Trident to render the "Store" and "Update News" sections
Windows Help, from Windows 98 onwards
Windows Media Player, which uses Trident to render the "Media Information" pages; other media players, such as Winamp and RealPlayer, have similar features.