Google Trends is a very useful service that allows you to find the search trends for any particular keywords. In addition to that you can also use Google Trends to compare trends between multiple websites.
Hot Trends is a feature in Google Trends, which allow you to see the hottest searches performed on the web in the last 1 hour. You can view the Hot trends for any location by changing the top level domain. For example, using google.com/trends/hottrends will show you the hottest search terms in USA. Using google.in/trends/hottrends will show you the hottest search terms from India.
Google announced the integration of hot trends into Google search results for users in USA and Japan. Starting today whenever you search for keywords that are in Hot Trends you will see hot trends in the search results.
This feature will show up in search queries that rank in the top 100 hot trends.
Keep up with the latest trends using Google Search [Official Google Blog]