Take the example data on the right. It shows resources, connected to each other by edges. The rectangular blocks denote the resources, the arrow between them denote the edges.

It shows the *domain model* of a basic blog-like structure:
article resources which are written by persons and articles being
tagged with keywords.

The edge between Alice and cooking for dummies is labelled author: indicating that Alice wrote that article.

Note that these edges have a direction. When reasoning about edges, it is the easiest to think of them in terms of grammar: Subject - verb - object. In the case of Alice:

**Cooking for dummies**is authored by**Alice**;**Cooking for dummies**has the keyword**Cooking**;

or more general:

**subject****predicate****object**.

In Zotonic, the terms subject and object (shortened as s and o) are used in the templates, allowing you to traverse the edges between resources:

```
{{ m.rsc[id].o.author[1].title }}
```

Returns the name of the first author of the article with the given
id, by traversing to the first author object edge of the
given id. See the *m_rsc* model for more details on this.