Explain the purpose and operation of sessions in the context of Django ORM.

In Django ORM, a session is not used directly, as in SQLAlchemy. Instead, Django manages database connections and transactions automatically.

However, if we talk about a session in the context of working with a database, it can be understood as a period of interaction with the database during which operations are performed. Django ORM ensures the atomicity of operations through transactions, which can be controlled using decorators or context managers.

Example of using a transaction:

from django.db import transaction

with transaction.atomic():
    # database operations
    obj.save()
    # if an exception occurs, changes will be rolled back

Thus, a session in Django is more about managing transactions and connections, provided by the framework, rather than an explicit object like in some other ORMs.