Recall from Chapter 3, we described RSS 1.1 as being RDF-based. What exactly is RDF? Many call RDF “metadata about data” and then go on to describe how it has evolved beyond that. While RDF and its usage has certainly evolved, it is important to not to forget the “metadata about data” aspect because it captures the essence of what RDF is.
The purpose of RDF is to describe a web resource, that is, to describe something on the Internet. For example, if a shopping website lists the price of something, what exactly is a price? Is it in American Dollars? Mexican Pesos? Russian Rubles? For a website, what exactly is a timestamp? Should a machine parser treat a timestamp in 12-hour notation different from a timestamp in 24-hour notation? XML, at a very high level, was supposed to allow groups to standardize on a transaction format. Implementation details were left to the parties of interests because XML is just a language. RDF is the next evolution of that original...