REST architectural style and so, a resource is any information that can be named a document, an image, even something that's temporal, changing over time a collection things like that so, as long as it's addressable then, it can be a resource which sounds really general but that's what it actually is so, the representation is the presentation of a particular resource so, you may have a JSON, or an XML representation of a resource but the resource is still the same content but the representation has changed so this is, if you think about, like : if you have a news article, that's written in English, but is also tranlated into Spanish, and into French you could think of the abstract idea of what the article is saying is the resource itself and then you would have representations in different languages so, it's about the core data and then the way that's displayed or interpreted %um and then finally, the biggest one : hypermedia so, hypermedia is one of those vague term we hear a lot, right we do web work here so, HTTP, HyperText Transfert Protocol basically, all hypermedia is is there has to be connections between you representations of your resources so you're able to browse if you will, through all the things that your API provides there's a little bit of a non-linear aspect to this, too although you could have linear links, obviously but, the idea is that you form a web of interconnected things which sounds silly to say in front of people who do web developement, but our APls don't actually operate like the Web does which is a problem because they're supposed to 