Reasons For A Decline In Search Engine Rankings

To say there may be plenty of reasons is not a good answer and will not do you any favours, instead you could mention potential reasons and even better, potential solutions.

1: Changes To Your Website
WebPages change regularly, there are always updates going on, small changes wont have a real impact on rankings, but a major over haul could.  If a website has been re-designed or if pages are optimised for different search terms then it is possible that the rankings will be re-calculated.

If a webpage is ranked highly for a competitive phrase, it should be edited with great care.

2: Changes To Links To Your Website
If a website is established and has many inbound links, then it’s unlikely that your site rankings will decrease because of it.  However if a link building campaign has been based around paying for links or even renting links, then these can either disappear or can get discounted. 

Buying links can never be considered a long term strategy, and link building should never stop if you wish to maintain a high search engine position.

3: Changes To Your Competitor Pages
Modern day search engines crave unique content. An important job in search engine optimisation is to build keyword rich content, if your website hasn’t been updated with relevant content for a while, it is possible that you could be over taken by competing websites.

4: Spam Elements
Spam elements such as cloaking or hidden text are not looked at too kindly by search engines.  If a website has this, then it is more than likely going to be penalised.

All spam elements should be removed if they are present, once they are you will need to play the waiting game.

5: Technical Issues
It is possible that the web server that is hosting a website can be to blame for a drop in rankings.  If a website is down when a search engine spider visits, it wont be able to rank the page.  As well as this, there are times where a server may display a page, but present an error code to the search engine spider.

Your website(s) should always be hosted on a reliable server that has no downtime. As well as this, check the HTTP status code that your website returns.
Almost any website owner will see a significant ranking drop sooner or later. Don't panic if this happens to you. Try to find the reason for the ranking drop and then act accordingly.

5. Search engine algorithm changes
Of course, Search engines are continually adjusting and improving their ranking algorithms. While most changes are rather subtle, some algorithm changes can have a huge impact on the rankings of web pages.

If you believe that you may have been punished in some way, try not to panic and wait for a few days to see if the ranking drop is on a temporary one.  If it is not, it’s time to research and implement the latest optimisation techniques.