Patreon is a site through which people can crowdfund their favourite creators (artists, bloggers, writers, gamers etc.) on a rolling, e.g. monthly, basis. In return people get 'rewards': perks such as exclusive content, customised content or discounts on something the creator already offers. Generally the more you pledge per month, the more rewards you get.
I'm researching why people do or don't want to pledge to creators. Please note most creators already offer something for free as standard (like a cartoon series, YouTube videos or a blog) and use Patreon to offer something more.