what's serial login
 

Hi,
When I complie my kernel it askes me if I want support for virtual terminal. When I say 'yes', it asks do you want support of console on virtual terminal. When I say 'yes', then it asks if I want support for serial login on virtual terminal.
Could anybody tell me what's all this about. What exactly is a virtual terminal and serial login. What are the devices that represent these things in /dev, etc.