Register through someone's referral link:
This means if someone sends you their link and you register through it, Binance rewards you with bonuses either for registration or for your first trade.
Airdrop means free distributions:
Sometimes Binance gives away free coins to people who participate in certain events or who hold specific coins.
There are daily or weekly tasks:
Binance has things called 'Missions', for example, when you log in every day or trade a specific coin, they reward you with some coins.
