There are typically two main types of airdrops:
1. **Standard Airdrops**: Users receive tokens for free, often by signing up with their wallet address or completing simple tasks like following social media accounts.
2. **Holder Airdrops**: Existing holders of a specific cryptocurrency automatically receive new tokens based on the amount they already hold.
Airdrops can be a great way to gain exposure to new projects, but it's important to be cautious, as some may involve scams or phishing attempts.