please help me how can I learn about IOT !! I am a beginner !! which should I have to know to make an IOT based projects?
There are lots of online resources to help teach you about IOT. Here is an example: https://www.youtube.com/playlist?list=PL9ooVrP1hQOGccfBbP5tJWZ1hv5sIUWJl
Again, there are many different resources. It’s a given that the ones you’ll pay for will be better but if you want to learn for free there are always great YouTubers sharing what they know with the world.