Semantic web

Attempting to make sense of the zoo of semantic web standards. For most public web work, this is just about getting your content into rich presentations in search engines.

Vocabularies

Schema.org

Schema.org is a set of vocabularies for structured data on the web + a consortium for maintaining them. This is, more or less, how you make your content machine-readable for things like rich sinppets on Google and other search engines.

Plenty of other sets of vocabularies exist that I have not messed with, such as the Dublin Core specifications.

Formats

HTML documents can be annotated with metadata using a number of different formats, each with different advantages.

RDFa

RDFa is a way of adding metadata directly to your markup by means of attributes, as a serialization of RDF triples. It seems similar to Microdata, but more powerful (and also more complicated).

Microdata

Microdata adds metadata to HTML by means of attributes sprinkled directly onto the elements they annotate.

JSON-LD

JSON for Linked Data. This is an easy way to specify schema.org metadata in a single blob, without having to weave attributes into the site’s components. This seems to make it particularly easy to support in content management systems.

Microformats

Old, circa 2005.