By Mark Ward
Technology Correspondent, BBC News website
Microsoft's Silverlight software is starting to get some attention and here the BBC News website explains why the technology is important.
Without Flash sites like YouTube may not have been such a success
When Microsoft unveiled Silverlight at the NAB Show in April 2006, industry commentators instantly dubbed it a "Flash killer" and said it spelled serious competition for Adobe's widely used animating tool.
At first glance, Silverlight did seem to deserve the description as it seemed to be a tool chest that let designers and developers produce the same sort of animated and rich websites that Flash coders can.
But, as more details of Silverlight emerge, it is clear that calling it a "Flash killer" is to seriously underestimate Microsoft's ambitions for it.
It is true that Microsoft does want to displace Adobe's Flash perhaps because that software has proved so useful to so many hugely popular websites.
It can be argued that without Flash, websites such as YouTube would not have become so successful so fast.
But with Silverlight, Microsoft is also taking aim at a much larger swathe of technologies, all of which are behind the growth of all those sites lumped together under the Web 2.0 banner.
Web 2.0 is a slippery portmanteau term that describes both a series of technologies and an attitude.
Ray Ozzie talked up Silverlight at the Mix 07 show
Web 2.0 sites tend to have large committed communities and many of those sites give them a series of tools to make more of the content seen or stored on that site.
Classic examples of Web 2.0 sites include Flickr, MySpace and NetVibes - all of which are in the business of making it easy for their users to do a lot with the pictures they take, friends they gather or news and blogs they want to read.
Building those tools involves a range of technologies with formidable acronyms that, crucially, Microsoft does not own or control.
A clue to how Microsoft wants to use Silverlight to become a big player in the tools for creating rich websites came at the Mix 07 conference held at the end of April.
At the conference, Ray Ozzie, Microsoft's chief software architect and the spiritual heir of Bill Gates, said: "The Web apps of today, and the Web apps of tomorrow are by necessity complicated, and fragmented across many technologies."
In his speech, Mr Ozzie unveiled a new version of Silverlight, release 1.1, that Microsoft hopes will solve some of those fragmentation problems.
With the new release Microsoft made it possible for almost every programmer who develops software using the firm's tools to produce code that can feed into a Silverlight application.
At a stroke that vast army of developers, who Microsoft has always assiduously courted, suddenly got the ability to write code that can be used to power rich Web 2.0 sites.
As Mr Ozzie said, this includes those who write code for servers, PCs, web browsers, mobile devices or game consoles.
Suddenly, said Mr Ozzie, developers had a "new choice" for creating those compelling futuristic web applications.
All those developers no longer need to go through the tricky route of converting their original code to a format that Flash can understand - Silverlight will understand it untranslated.
Silverlight lets existing developers crank out web code
It goes without saying that a browser running a Silverlight application needs a Microsoft server to hand over the rich content.
It is here that the Redmond giant hopes to make some money and claw back some credibility with web developers.
In a sense, Microsoft had to develop a tool that could do this if it wanted to become a serious player in the future of the web.
"It would have been a mistake not to do it," said Matteo Berlucchi, boss of UK developer Skinkers which has wholeheartedly embraced Silverlight.
It is one of the ironies of the Microsoft story that just as its dominance on the desktop was assured, focus moved to the internet where it had almost no control. Silverlight is an attempt to win back some control.
But Microsoft's history could mean that Silverlight takes time to become established.
The numerous anti-trust cases against Microsoft mean that it is unlikely that it will simply be able to bundle it in with other Microsoft programs. Instead users will have to download and install it themselves.
In that respect there may be something of a brake on the spread of Silverlight even if there is no limit to Microsoft's ambitions for it.