Two weeks ago, my site is placed in google in first page, place 11, for one keyword, after one week place 18, and today place 9.
This is the google dance ?

Depending on many factors rankings fluctuate all the time, especially for medium and low competed keywords.

I have had similar situations. If you want to keep track of the fluctuations and also be able to track when you need to tweak your keywords get an analytics package that allows you to run web statistics on a regular basis.

hi

due to the revolution in the field of seo every one wants to be a no. 1 rank on the google thats why no web site can remain on the number one rank for long time.

This might be a Google Dance. Google's index update occurs on average once per month. It can be identified by significant movement in search results and especially by Google's cache of all indexed pages reflecting the status of Google's last spidering. But the update does not proceed as a switch from one index to another at one point in time. In fact, it takes several days to complete the index update.

I tend to agree with seopositive. SEO has become such a hot topic and so many people are putting so much work into it that it is hard to maintain the number 1 spot unless you really have cornered the market or have something to offer that is really unique.

I have experience the same situation too!.. It must have been the effects of Google dance.. Most of our rankings goes up and then down when google made some updates.. It actually takes two or even more before google finishes all the updates.. Try to check it and see the results.. Hope you'll get positive results..

Yesterday my site on 86 place in google
What do you think ?

There is a lot of rumour that Google is changing a few things at the minute, many people are noticing that rankings are flying up and down right now. Add in the two recent PR updates and the move to brand authority and I think there are plenty of reasons why sites are bouncing around right now.

thank you for reply. i think this is not for long time.