IF DNT is true, then the browser's Do Not Track is turned ON. If false or unspecified, then OFF.
At the moment of writing, most ads networks will not honor Do Not Track status. Browser based add-on like Privacy Badger will be able to tell you which trackers will honor or ignore the Do Not Track status. In the long run, it will be wise to respect a visitor's decision to turn on Do Not Track.
Special thanks to Mr. Джон Сора of Russia for introducing Privacy Badger to me.
IF you gain some knowledge or the information here solved your programming problem. Please consider donating to the less fortunate or some charities that you like. Apart from donation, planting trees, volunteering or reducing your carbon footprint will be great too.