You have to complete various social tasks, for example, join Telegram group, or follow the project on twitter or some other social network
Ok... It's more or less clear, airdrop gives you free coins. So does bounty! So what is the difference between airdrop and bounty?
Well, they are basically the same in terms of what you get...But the tasks are different
Airdrop is just basically free coins. In bounty campaigns you sell your services (posts, youtube videos, translations and etc)