Why Google Trends?
Everyone knows that google search engine is most used and drive the traffics in your site. So Google have all data about interest of users by their topics, terms  and according to country. So Google trends is most useful to check trends of your topics in future, past and present.

In Post have one Topic of your post and another is contents related to your topics. Contents of topics doesn't matter to takes first your site in search engine result than to more valuable is Topic Post Name. 

How to use Google Trends?
Google trends is very awesome tools for search what people search in google. Google Trends provide Two tools. First is Explore Trends and second is Hot searches. Explore trends given an information of search from 2004 to today, while hot searches given an information about recent high searched query.You can searche  in Explore Trends according to country, time period, categories, type of search(web, image, video, product). Explore trends updated daily while hot search updated hourly.