What is Flash and is it acceptable to use it on an accessible Web site?

Flash is a popular authoring software developed by Macromedia and is used to create vector graphics-based animation programs. A Flash solution is fairly easy to implement on a Web site but the site will then be usable only by modern browsers which have a Flash plugin.

The problem is Flash is a proprietary solution, which is owned by Macromedia which means it may not be accessible and will probably not work on non-standard devices, such as a digital TV.

As with any proprietary solutions there are dangers in adopting it as a solution: there is no guarantee that readers will remain free in the long term, readers (and authoring tools) may only be available on popular platforms, the future of the format would be uncertain if the company went out of business, was taken over, etc. The company is at liberties to make changes to the format or to change the licence conditions governing use of the format (including software to create files and software to view files).  Use of proprietary formats leaves the user hostage to fortune - for example the owner of a popular and widely-used format may increase the costs of its software (or introduce charges for viewing software).

It is also worth noting that indexing software, etc. often cannot index proprietary formats, so it can act as a barrier to resource discovery. Also there may be accessibility considerations, to users using old or specialist browsers.

The general advice is that where the job can be done effectively using non-proprietary solutions, and avoiding plug-ins, this should be done. If there is a compelling case for making use of proprietary formats or formats that require the user to have a plug-in then you could use the format as long as an alternative was available.

If you *require* the functionality provided by Flash, you will need to be aware of the longer term dangers of adopting it.  You should ensure that you have a migration strategy so that you can move to more open standards, once they become more widely deployed.

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