This is very helpful tool provided by the Google freely. Main aim of this tool is to improve our websites. It will show exactly what is going on our website and what the problems in our websites are. So that we can find what Google thinks of our site. This also prevent from us from being blocked. It can help index our webpage more effectively. It is very similar to the Google analytics but carrying both tools will help you to get full image of your website and what needs to be improved.