Method decorators is most important part of the Odoo, it method decorators provides the elements for managing two different API styles, which is "traditional" and "record" styles.
In the "traditional" style, parameters like the database cursor, user id, context dictionary and record ids are passed explicitly to all methods. In the "record" style, those parameters are hidden into model instances, which gives it a more object-oriented feel.
For example you can see below code-

model = self.pool.get(MODEL)
ids = model.search(cr, uid, DOMAIN, context=context)
for rec in model.browse(cr, uid, ids, context=context):
    print rec.name
model.write(cr, uid, ids, VALUES, context=context)
env = Environment(cr, uid, context) # cr, uid, context wrapped in env
model = env[MODEL]                  # retrieve an instance of MODEL
recs = model.search(DOMAIN)         # search returns a recordset
for rec in recs:                    # iterate over the records
    print rec.name
recs.write(VALUES)