Watch Alexi Douvas from Google explain how to know which search terms are driving traffic to your website in this video.
The first step is to make sure your website is verified in the Google Webmaster Tools control panel. Google gives some easy to follow instructions there, but you will need access to your source code and/or access via FTP to your server.
Once verified in the query section, you can actually see and sort data that shows how many times your website was shown for specific search queries, how many times readers clicked into your website and where on Google.com your site appears in the search rankings.
A high click through rate but low number of impressions is not a good thing. You’ll want to review your meta titles and content to try to boost exposure. By reviewing your search query list you can also evaluate how well your website is doing in regards to reaching a broad base of potential prospects. If all you see if your name or phrases that really don’t match your service offerings, now’s the time to carefully review your content’s focus.
What Google shows in the query list is based on historical data. If you see keywords that have a gambling or adult content focus and your site does not provide or sell these services, your website has most likely been hacked and needs a very careful review.