The recent announcement by Google that it has started indexing the contents of Flash files was welcomed by many webmasters, but brought with it a whole new set of optimisation issues.

Traditionally, optimisation of Flash-only sites involved not much more than the inclusion of an HTML version of the content as a way of allowing the search engines to index it correctly. Similar workarounds were used for sites that used Flash elements as part of the mix, to get around the search engines' inability to handle Flash files.

As an SEO, knowing one basic rule (namely: "search engines don't index Flash, advise against it and work around it") was usually a pretty safe bet that yielded visible results.

The recent changes (which so far will affect Google and Yahoo) bring with them the need for SEOs to delve deeper into the mechanics of how Flash works, in order to see how various ways of doing things will affect a site's ranking.

Suddenly, the backup HTML versions of the site will be treated as duplicate content and there is already talk of certain types of animations causing duplicate content issues within the Flash content itself.

Different ways of triggering the animations could also now affect the way Flash content is indexed, calling for a new set of SEO best practices.

This highlights one of the key issues about search marketing - the fact that it is a constantly changing and evolving industry.

As usual, all it took was one announcement from Google to close the door on a whole assortment of solid, white hat SEO tactics and force search professionals to start learning a whole set of new ones.

Of course, this sort of thing happens all the time and makes for some interesting challenges. When working with established websites, I've often come across SEO legacy issues needing to be resolved. Tactics that were considered all the rage a few years ago, or even sooner than that, can and do become obsolete on a regular basis.

Things that were considered to be above board (or tolerated) in the past can and do become offences punishable by dreaded Google penalties.

Without an understanding of the nature of the world of SEO, it can be hard to understand how something that has worked and propelled a site up the rankings can now be seen to be dated and harmful. This recent announcement will undoubtedly pass some people by. I'm sure we'll be seeing plenty of sites still conforming to the old pre-Flash rules in years to come.

Often, I find that the main challenge in fixing legacy issues is not the actual updating of the SEO strategy, but convincing the people in charge that these changes are timely and necessary.

When you've put a lot of time and effort into devising a working strategy, you may well be reluctant to change the whole thing around, especially when this involves expending further time and resources on something you thought was done and dusted.

To make matters worse, there are some elements of SEO that are more or less the same now as they were years ago, meaning that you can't draw conclusions from the long-term suitability of one tactic to another. Unless you are involved with active optimisation projects on a daily basis and spend time catching up on trends and changes such as the recent Flash announcement, you may be quoting yesterday's rules that no longer apply. The one thing to keep in mind is that nothing in the world of search is set in stone.

Shimrit Elisar