Cards are Wagn's building blocks. They're like atoms of data that can be combined and connected to create all kinds of new data structures.
Many web systems have some parallel to cards. Wordpress has "posts", Drupal has "nodes", etc. But Wagn takes the atom idea much further. For example, if you have a Company card (say Widgets, Inc) that you want to attach several smaller bits of information (address, logo, contact person, etc), then each of the smaller bits of information is also a card.
In contrast, to add microstructure to a Wordpress post, you must create new custom something-or-others that themselves are not posts. The same goes for Drupal nodes. These custom something-or-others can require custom interface, custom code, and custom database tables, none of which are familiar to the rest of the system. A standard site might have half a dozen modules installed, each with custom subsystems that have no idea that the others exist. This makes data and system integration extremely difficult.
Wagn's deeply atomic approach yields huge benefits. Since everything is a card, you can use the same data and interface patterns over and over again. Everything can be edited in place, without shifting context. There's just one modules api, one RESTful Web API, and one rule system. The native query language is designed for querying cards, and the views system is designed to display them.
In short, Wagn just does one thing: it handles cards. But that one thing adds up to an extremely powerful yet simple management tool
understand card structure
A card is essentially a key/value pair. In Wagn terms, every card has a "name" that serves as its key and "content" that serves as its value.
Both the key and the value have plenty of added meaning/power within Wagn. Card names, for example, handle variants, compounds, and context, and card content has special handling for types, revisions, formatting, links, and inclusions.
But ultimately a card isn't a scary thing. It's just a named chunk of information .
Since everything in Wagn is a card, learning how to use cards is basically the same as learning how to use Wagn. You can start with a high-level introduction to wagneering or go straight to lower-level features.
Just one: try it out. It's easiest to learn the card game by playing it.
Also see: Tickets tagged with "card creation"