python-quantumclient is a Python module that provides client functionalities for Quantum.
Quantum is a virtual network service for Openstack.
Just like OpenStack Nova provides an API to dynamically request and configure virtual servers, Quantum provides an API to dynamically request and configure virtual networks. These networks connect "interfaces" from other OpenStack services (e.g., vNICs from Nova VMs). The Quantum API supports extensions to provide advanced network capabilities (e.g., QoS, ACLs, network monitoring, etc).