Google Trends is a public web facility of Google Inc., based on Google Search, that shows how often a particular search-term is entered relative to the total search-volume across various regions of the world, and in various languages.
The horizontal axis of the main graph represents time, and the vertical is how often a term is searched for relative to the total number of searches, globally.Below the main graph, popularity is broken down by region, city and language. It is possible to refine the main graph by region and time period.
Video tutorial on Google Trends:
GOOGLE INSIGHTS FOR SEARCH
Google Insights for Search is a service by Google similar to Google Trends, providing insights into the search terms people have been entering into the Google search engine.
Unlike Google Trends, Google Insights for Search provides a visual representation of regional interest on a country's map. It displays top searches and rising searches that may help with keyword research. Results can be narrowed down with categories that are displayed for each search terms.