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+##########
+Data Model
+##########
+
+*********
+Structure
+*********
+
+Serd is based on RDF, a model for Linked Data.
+A deep understanding of what this means isn't necessary,
+but it is important to have a basic understanding of how this data is structured.
+
+The basic building block of data is the *node*,
+which is essentially a string with some extra type information.
+A *statement* is a tuple of 3 or 4 nodes.
+All information is represented by a set of statements,
+which makes this model structurally very simple:
+any document or database is essentially a single table with 3 or 4 columns.
+This is easiest to see in NTriples or NQuads documents,
+which are simple flat files with a single statement per line.
+
+There are, however, some restrictions.
+Each node in a statement has a specific role:
+subject, predicate, object, and (optionally) graph, in that order.
+A statement declares that a subject has some property.
+The predicate identifies the property,
+and the object is its value.
+
+A statement is a bit like a very simple machine-readable sentence.
+The "subject" and "object" are as in natural language,
+and the predicate is something like a verb (but much more general).
+For example, we could make a statement in English
+about your intrepid author:
+
+   drobilla has the first name David
+
+We can break this statement into 3 pieces like so:
+
+.. list-table::
+   :header-rows: 1
+
+   * - Subject
+     - Predicate
+     - Object
+   * - drobilla
+     - has the first name
+     - David
+
+The subject and predicate must be *resources* with an identifier,
+so we will need to define some URIs to represent this statement.
+Conventionally, predicate names do not start with "has" or similar words,
+since that would be redundant in this context.
+So,
+we assume that ``http://example.org/drobilla`` is the URI for drobilla,
+and that ``http://example.org/firstName`` has been defined as the appropriate property ("has the first name"),
+and can represent the statement in a machine-readable way:
+
+.. list-table::
+   :header-rows: 1
+
+   * - Subject
+     - Predicate
+     - Object
+   * - ``http://example.org/drobilla``
+     - ``http://example.org/firstName``
+     - David
+
+Which can be written in NTriples like so::
+
+  <http://example.org/drobilla> <http://example.org/firstName> "David" .
+
+*****************
+Working with Data
+*****************
+
+The power of this data model lies in its uniform "physical" structure,
+and the use of URIs as a decentralized namespace mechanism.
+In particular, it makes filtering, merging, and otherwise "mixing" data from various sources easy.
+
+For example, we could add some statements to the above example to better describe the same subject::
+
+  <http://example.org/drobilla> <http://example.org/firstName> "David" .
+  <http://example.org/drobilla> <http://example.org/lastName> "Robillard" .
+
+We could also add information about other subjects::
+
+  <http://drobilla.net/sw/serd> <http://example.org/programmingLanguage> "C" .
+
+Including statements that relate them to each other::
+
+  <http://example.org/drobilla> <http://example.org/wrote> <http://drobilla.net/sw/serd> .
+
+Note that there is no "physical" tree structure here,
+which is an important distinction from structured document formats like XML or JSON.
+Since all information is just a set of statements,
+the information in two documents,
+for example,
+can be combined by simply concatenating the documents.
+Similarly,
+any arbitrary subset of statements in a document can be separated into a new document.
+The use of URIs enables such things even with data from many independent sources,
+without any need to agree on a common schema.
+
+In practice, sharing URI "vocabulary" is encouraged since this is how different parties can have a shared understanding of what data *means*.
+That, however, is a higher-level application concern.
+Only the "physical" structure of data described here is important for understanding how Serd works,
+and what its tools and APIs can do.