Viden.io is a great platform.The day I came across this I regretted that why didn't I know about it earlier.Being a student,we do need notes , previous year question papers, answers ,solutions and what not. And we hardly have time to go through all the sites on internet.Viden.io saves time and provides us with the best results possible to what we are searching.The best part is students can upload too. It's extremely useful. You can get help and you can help others too.