True, this field is the primary key for the model.
If you don’t specify
primary_key=True for any field in your model, Django
will automatically add an
AutoField to hold the primary key, so you
don’t need to set
primary_key=True on any of your fields unless you want to
override the default primary-key behavior. For more, see
Automatic primary key fields.
The primary key field is read-only. If you change the value of the primary key on an existing object and then save it, a new object will be created alongside the old one.