Google offers website owners two tools to help analyze their websites. You need both.
This is the most popular analytics site. You set it up using your Google account and it gives you a lot of useful information, such as number of visitors, what pages they looked at, how long they stayed, and much more. The one area it no longer gives information on is search terms people used to find your site. In 2013, Google finished implementation of a new search method that is more secure, but results in Google Analytics reporting almost all search terms as “(not specified)”. This is not helpful, but it is necessary to have the added security of the new method.
Google Webmaster Tools
Google webmaster tools gives more technically oriented information. It reports any errors Google has found with your site, which you should fix in order to rank better. It is now the only Google tool that will report what search terms were used to find your site. It shows how many times your site appeared in the listings when that term was searched, where you ranked, and the proportion of searches that resulted in a click to your site. When you are setting up Google Analytics, use the option to also set up Google webmaster tools.