What Are DVD-RAM Disks?

Bob asks, What are DVD-RAM disks?
The simple answer is DVD-RAM is a physical disk data storage format relying on shiny disks for storage. Of the various DVD media types, DVD-RAM is probably the best suited for data backups because it includes some features for routing around defects and zoning the physical disk for quick access to information stored on disk. In this sense, the way an operating system addresses a DVD-RAM disk, it’s not unlike having a 4.7GB hard drive for storing data, without all the potential for failure if you accidentally drop the disk.
DVD-RAM is probably best described as a removable storage device, rather than a traditional recordable DVD (like DVD+R or DVD-R). Think of a DVD-RAM disk as a hard drive the size of the other shiny coaster formats. The disks first appeared around 1998 with a 2.5GB capacity, which was huge for removable media at that time. In 1999, capacity increased to 4.7GB, which matches single layer DVD-ROM specifications as well.
DVD-RAM disks come in two flavors: a cartridge protected variety, similar to the old Zip disks, with the disk protected inside a plastic sleeve; in some cases these disks are two-sided. More common are the individual shiny platters like you might expect from the more common DVD-R or DVD+R media.
Assuming you have an optical drive with support for DVD-RAM, Windows XP is capable of writing directly to a DVD-RAM disk, just like it would a hard drive. The caveat to this is the DVD-RAM disk must be formatted FAT32 (not UDF) in order for Windows XP to access the disk directly. Older versions of Windows require software intervention for appropriate support. The two places you are most likely to see DVD-RAM in the consumer space these days is in a recent generation of Toshiba laptops and in a few of the set top DVD Recorders.