It was listed on the first page of Google's search results for my main key phrase for well over a year, then it suddenly dropped to the bottom of the third page last week. What could be the reason for the dramatic change? I haven't made any major changes to the site recently. Why did my website drop out of the Google top-10?
Could be any number of reasons. What did you do recently off site? For example. Linked to anywhere dodgy recently by any chance?
Agree with Decoder. Just check out what you have been done recently of your site, so you can find the reason.
My answer to you will be short...duplicate content. Write some original content and you should be golden.
Yep I agree with you, The first reason that made you outranked your competitors for a year, is probably the same thing they've done to outrank your site now.
It seems that a lot of people here believe that links are the holly grail of ranking. Its not. Dont get me wrong, it is definetily a component of encreasing your first page exposure. The truth is that there are other factors that go in to the calculation. These days, you can not just do one or the other part of SEO. Its a big puzzle; you need to try to solve the whole thing.
You keywords ranking come down because your competitors are getting backlinks with high pr sites which increase the ranking of their websites.