The EFI community has formed an open source shell environment. Rather than booting directly into a full OS, on some executions, the user can boot to the EFI shell. The shell is an EFI application; it can reside straight within the platform ROM, or on a device for which the drivers are in ROM.
The shell can be used to implement other EFI applications, such as setup, OS install, diagnostic or configuration utilities, and system flash updates; it can also be used to play CDs or DVDs without having to boot to a total operating system, given that an EFI application with the appropriate features is written. Shell commands also make it possible to copy or move files and directories among supported file systems. Drivers can be loaded and unloaded, and a whole TCP/IP stack can also be used from within the shell.