Riding The Flux
Search engines employ spiders to crawl the web page by page and not only do these spiders index initial information that they find but they also update information on existing pages. As the crawling rate for many websites and pages has increased this means that search engine results can change dramatically even in a very short space of time. Where your page may have only been number four or five in the search results one day, it may hit the top spot the next day and vice versa.
This constant changing of search results is referred to as a state of flux and the experienced SEO knows that results are constantly changing. While novice SEOs and website owners may panic or celebrate when their sites first enjoy or endure this experience, the more experienced will know that it can change back again just as quickly. In most cases, the more active your SEO efforts and the better quality links you build, the quicker your site will climb the rankings meaning greater activity and a greater realisation that the flux of the index is a natural occurrence.
Riding the flux should become a part of your everyday SEO life. Some changes to your rankings may be caused by one specific action you have taken or it may be a result of an algorithm update. Alternatively, it may just be that months of inactivity or months of SEO campaign are finally beginning to catch up with you and your ranking is changing as a direct result of this.