what is Google trend and how can it work? what is the up gradation time of
Google trend?

Its a free Google service that provides charts that show how often words, phrases and topics have been searched for over time. Google trends allows to users if they want to compare 2 keywords search graph.

You go to google.com/trends.Then you type a search query.You hit enter.The chart that comes up shows how much it is searched on google inthe past years.

Google Trends is a tool from Google Labs. It give permission you to see how Google search volumes for a particular keyword have changed over a period time.