Short answers, pulled from the story.
A CD-ROM is a read-only optical disc that stores data as microscopic pits and lands on a reflective polycarbonate surface. A 780 nm laser reads the pattern by detecting changes in the reflected beam's intensity caused by the pit depth. A standard 120 mm CD-ROM holds 650 MB in Mode 1 format, or 703 MB on an 80-minute disc.
The CD-ROM standard was created by Sony and Philips in 1983 in a document called the Yellow Book, building on earlier work by Toshi Doi and Kees Schouhamer Immink. It was announced in 1984 and introduced at the first Japanese COMDEX show in 1985. The first public CD-ROM drive, Philips' CM 100, shipped in July 1985.
One of the first products made available to the public on CD-ROM was the Grolier Academic Encyclopedia, presented at the Microsoft CD-ROM Conference in March 1986.
Mode 1 uses 2,048 bytes per sector for data and adds error detection and correction bytes, making it suited for general digital data. Mode 2 allocates 2,336 bytes per sector for data by omitting error correction, making it better suited for video or image content where minor errors are tolerable.
The 1x speed rating for CD-ROM is 150 kilobytes per second, derived from the CD audio standard. By 2004, the fastest commonly available drives reached 52x, delivering approximately 7.62 MB/s at around 10,400 rpm. The Kenwood TrueX 72x drive used seven laser beams at roughly 10x rotation to achieve 72x throughput without extreme spin speeds.
DVDs and downloading replaced CD-ROMs starting in the early 2000s. A single-layer DVD-ROM holds 4.7 GB of error-protected data, more than six standard CD-ROMs, and consumer DVD drives delivered 36x CD-ROM equivalent speeds from the start. Commercial use of CD-ROMs for software distribution is now rare.