SERP stands for Search Engine Results Page and is what you get after a keywords query in a search engine: a list of results that normally include a title, a URL and a short description pointing out where the keyword inputted matches the text and, depending on the type of the result, other elements might as well be displayed (e.g. the upload date in a blog post).
How are the lists generated?
There are many search engines – the major of which are Google, Yahoo! And Microsoft’s Bing – and they generally tend to use different methods to determine their SERPs eventual results. SERPs display organic listings, meaning listings generated by some algorithmic formula that quantifies their relevance to the word or set of words you typed. There is also the possibility of paid listings, aka sponsored links, images, videos etc. being displayed alongside the rest of the results.
What do these all mean for a blogger?
SERPs include 10 listings each. Bearing in mind that the listings on the first page get 91% of the traffic share, it is of vital importance for your article to appear on the first page of any respective search, for it is highly likely it will be clicked! Then, of course, it is even better to be listed on top given that the top 3 positions get the majority of the traffic: the first listing has an average traffic share of 32.5 %, the second 17.6 % and the third 11.4 % (the percentages of the rest follow a gradual decline).
This short analysis illustrates how important the use of keywords is for a blogger. By picking the right keyword, you could have your blog or a particular post displayed in the first page, in the top 3 or even as the first listing, that way securing that you will receive as many visits as possible.
 SOURCE: http://www.seo-takeover.com/case-study-click-through-rate-google/