Omeka S provides an application programming interface (API) that enables CRUD operations on its resources. API resources are objects with a type, associated data, relationships to other resources, and sets of methods that operate on them. There are two ways to access Omeka's API:

Operations

You can perform these API operations on almost every API resource:

Operation Description
search Get a list of resources given query parameters
read Get an individual resource given a unique identifier
create Create a new resource
update Update an existing resource given a unique identifier
delete Delete an existing resource given a unique identifier

Resources

Omeka comes with the following API resources:

Resource Description
users Users who have login credentials
vocabularies RDF vocabularies imported into Omeka
resource_classes RDF classes that belong to vocabularies
properties RDF properties that belong to vocabularies
items Item RDF resources, the building blocks of Omeka
media Media RDF resources that belong to items
item_sets Item set RDF resources, inclusive set of items
resource_templates Templates that define how to describe RDF resources
sites Omeka sites, the public components of Omeka
site_pages Pages within sites
modules Modules that extend Omeka fuctionality (search and read access only)
api_resources API resources available on this install (search and read access only)

Do not confuse "API resources" and "RDF resources." RDF resources are resources that can be described and semantically linked using RDF vocabularies. The only RDF resources in Omeka are items, media, and item sets. (See Resource Description Framework.)