There are 2 main models or types of crowdfunding. The first is what’s called donation-based funding. The birth of crowdfunding has come through this model, where funders donate via a collaborative goal based process in return for products, perks or rewards.
The second and more recent model is investment crowdfunding where businesses seeking capital sell ownership stakes online in the form of equity or debt. In this model, individuals who fund become owners or shareholders and have a potential for financial return, unlike in the donation model.
There are more than 450 crowdfunding platforms active in the world -- below are a few examples.
Crowdblog on Fundraising