Are Virtual Network Interfaces, vSwitches ?

Hello all,

I am reading the following document http://www.vmware.com/files/pdf/dmz_virtualization_vmware_infra_wp.pdf

And on page 7 where it says "Set Layer 2 Security Options on Virtual Switches
Protect against attacks such as data snooping, sniffing, and MAC spoofing by disabling the promiscuous mode, MAC address changes, and forged transmissions capabilities on the virtual network interfaces."

How do I interpret the virtual network interfaces ? Are those the vSwitches or VM Port Group ?

Thanks for ur help,