After placing a blank DVD in the tray of a DVD writer and closing it, the disc begins to spin. This is because the laser that the drive uses to read and write information can only access all files on the disc at the same time if it is spinning.
Within a DVD-burning piece of software, a user can select which files and folders they wish to eventually burn to a DVD. With a single-layer DVD, a user can fit just over 4 gigabytes of information on one disc. With a dual-layer disc, it is possible to fit double that, but a special drive will be required. When the user finalizes what she wishes to burn and begins the process, the writer begins to convert the data into a signal that can be transmitted via laser.
A circular track of data is contained on every writable layer of a DVD. Via the drive's laser, data is transferred to each track of data until full. After all data has been transmitted, the disc is finalized, which means that its contents can no longer be changed (unless it is specifically noted as a rewritable disc, and the user is burning with a rewritable drive, both of which require a different kind of laser). The disc and its contents can then be read on any DVD-ROM drive connected to a computer.