The BIOS may be “manually” updated by a user, using a small utility program. In contrast, firmware in storage devices (harddisks, DVD drives, flash storage) rarely gets updated, even when flash (rather than ROM) storage is used for the firmware; there are no standardized mechanisms for detecting or updating firmware versions.

(Source: Wikipedia).

In Unix-likeoperating systems, a device or special file is an interface for a device driver that appears in a file system as if it were an ordinary file. There are also special files in MS-DOS and Microsoft Windows. They allow software to interact with a device driver using standard input/outputsystem calls, which simplifies many tasks and unifies user-space I/O mechanisms.

(Source: Wikipedia)

An ISO image is an archive file of an optical disc, a type of disk image composed of the data contents of every written sector of an optical disc, including the optical disc file system.[1 ] ISO image files usually have a file extension of .iso. The name ISO is taken from the ISO 9660 file system used with CD-ROM media, but what is known as an ISO image might also contain a UDF (ISO/IEC 13346) file system (commonly used by DVDs and Blu-ray Discs).

ISO images can be created from optical discs by disk imaging software, or from a collection of files by optical disc authoring software, or from a different disk image file by means of conversion. Software distributed on bootable discs is often available for download in ISO image format and, like any other ISO image, may be written on, or "burned" to, a CD or DVD with any capable software.

(Source: Wikipedia)