Dumb terminals, sometimes dubbed glass teletypes, display text on a screen, usually in monochrome, and allow the user to send to commands to the server computer to input or display data, or to preform some action. They include limited processing power to enable them to issue simple commands ('escape sequences') for clearing the screen and positioning the cursor. Some later terminals included a limited graphic display capability.
Smart terminals provide additional resources to perform local editing and simple processing. Basically, such smart terminals (often referred to as network computers or simply NCs) are low-cost PC platforms with no external storage like hard-disks or CD-ROM drives booting from a server in the network.