tracking planes

After travelling extensively on business for 30 years I now look to the skies when they are clear and study the vapour trails of the many planes which are visible from my back yard.
First thoughts are where are they going and from where.How high, what type of aircraft.???
Now I can answer these questions and so can you if you are so inclined.
Just click on www.flightradar24.com
You will be amazed .