I’m using YouTube since last 5 years it’s a platform where you can find & learn anything you like the support by YouTube to people is very strong & it’s service are amazing you can learn anything in YouTube & you will find all you information in depth the best app for learning is YouTube give a various verity of channel & video you will be happy if you use YouTube as a teacher . Their is three people who founded the YouTube us 1.jawed karim 2.chad hurley 3. Steve chen these three guys founded one of the best app you can earn money from youtube it’s make its more popular its is very easy to use YouTube you need to just search whta ever you want to see & you got it . It is not that much data friendly but ya its can be set graphics for smooth play the app is one of the best app I’m using! .