Why do keywords show "not specified" in Google Analytics?

Question

Google Webmaster Tools

If my user comes to my site using a specific keyword, google analytics shows "not provided" as the keyword. Why did this happen?
www.applepharma.ru

Answer 1

This is Google's data encryption policy.
You can see the search queries for which users come to you in google.ru/webmasters/
Well, connect Yandex.Webmaster and Metrika, there is more data about queries.