After [connecting](Connecting to Database), you can use the connection object (db) to define your models. You need to specify the name of the model, a specification of the properties and options (optional). Here's a small example:

var Person = db.define('person', {
  id:      {type: 'serial', key: true}, // the auto-incrementing primary key
  name:    {type: 'text'},
  surname: {type: 'text'},
  age:     {type: 'number'}
}, {
  methods : {
    fullName: function() {
      return this.name + ' ' + this.surname;
    }
  }
});

The model is called person (which is usually the name of the table in the database), it has 3 properties (name and surname as text and age as number). A default id: { type: 'serial', key: true } property is added if you don't specify any keys yourself. In this example there is a model method called fullName. Here's an example of the usage of this model:

Person.get(73, function(err, person) {
  if (err) throw err;

  console.log('Hi, my name is ' + person.fullName());
});

This would get person with id=73 and print it's name and surname. There are other types of [properties available](Model Properties).

/**
 * @param {Object} props Property definitions
 * @param {Object} opts Options
 */
db.define(props, opts)

The first object accepted by db.define() is referred to as the properties object. It defines all the properties.
The second specifies extra options: