After all these years, the fact still remains, that Flash has a much higher penetration, with nearly a 90%, even for its latest Flash 10 player. For mobile devices, Silverlight is almost non-existent, with only hints present of a future release, Flash once again reigns supreme. Although with a company like Microsoft behind the former, that is sure to change.

Even with the increasing adoption of Silverlight, it is surely not going to replace Flash player. There will be very few computers which with only the Silverlight player installed, and over time most people will have both players installed.

There are many reasons to still favour Flash Player: Besides its dominance in the computer and mobile segment, Flash player is available for Windows, MacOS, Linux and Solaris, and Adobe is working on bringing the full featured Flash Player to TV / Set-Top boxes, and mobiles. Microsoft Silverlight on the other hand is Windows only. While Microsoft does support Novell and the open source community in developing Moonlight (an open source implementation of Silverlight), its latest release currently supports only Silverlight 1 applications.

Flash has been around for a very long time, and it has come a long way from a simple vector animation tool to what it is today. In its very first few versions, Flash did not even support a scripting language. Over time Flash became associated with annoying banners, and intro pages, however now it has become an incredibly powerful platform for creating web applications.

Silverlight on the other hand was released less than three years ago, and while the first release was a rather weak attempt, over its next two releases, it has become a strong competitor to Flash. While Flash still remains lucrative for its larger base, technically it is possible to accomplish the same task with either.

It is important to note, that while in its entire history of 10 versions, Flash content remains backwards compatible with all previously created content, except for a few security upgrades which might require some modifications server-side. Content created for Flash Player 1, over ten years ago will still work on Flash Player 10! Content you create today should continue to work in all future versions of Flash Player. Flash player is a small download (1.8Mb for Windows, 5.66MB for MacOS, and around 4MB for various Linux / Solaris systems).

Silverlight in its short history of three versions, has already abandoned JavaScript as its language in Version 1, and has a number of backwards compatibility issues between Silverlight 2 and 3. The plugin is a larger download -- 4.8MB for windows, 8.9MB for MacOS -- and is not available for Linux  Silverlight support for Linux is instead provided by Moonlight, which aims to reach full compatibility with Silverlight, but as of now, its version 2 is still in pre-release stage and supports only Silverlight 2 applications with a few Silverlight 3 features, while the released version 1 is compatible with Silverlight 1. Amusingly, while Flash still supports the now obsolete Windows 9x platform for Flash 9, Silverlight support is absent in them!

The large amount of improvements in Silverlight in its short lifespan have less to to with Microsoft's cunning genius and more to do with the evolution of technology. Flash 10 would certainly have been possible ten years ago, but the goal was to make it a technology that runs on even the slowest of configurations. The result is that today Flash is installed on over 90% of the worlds computers.

Silverlight still has to make up for its long absence as a competitor to Flash, and its pathetic attempt with its first release did nothing to help its cause. It has come a long way in a short while now, and if Silverlight's improvements to compete with Flash are anything to go by, I cant wait to see what Flash Player 11 will bring.