Explain what is meant by a model in Django and how it is used in application development.

In Django, a model is a class that describes the data structure and the logic for interacting with the database. Models are defined as subclasses of django.db.models.Model and contain fields corresponding to the columns of a table in the database.

A model is used for:

• Defining the database schema through fields (CharField, IntegerField, etc.).
• Creating, reading, updating, and deleting records in the database via ORM (Object-Relational Mapping).
• Validating data and defining business logic related to the data.

Example of a model in Django:

from django.db import models

class Product(models.Model):
    name = models.CharField(max_length=100)
    price = models.DecimalField(max_digits=10, decimal_places=2)
    in_stock = models.BooleanField(default=True)

    def __str__(self):
        return self.name

Thus, the model serves as a link between the application and the database, allowing data to be worked with at the Python object level.