Hi,
Chances are that you're thinking about "runserver", which is a management command. On Unix based systems (i.e. Linux or MacOS) you start it with :
./manage.py runserver
I'm not exactly sure about Windows, but it should be something as :
python manage.py runserver
Warning : as stressed in the documentation, this is not a server to be used in production and it is reserved to development and local tests.
Eric