From (very roughly) 1989 through to the early 2000s, CD-ROMs (and later DVD-ROMs) were one of the primary ways to transfer heaps of software or large-sized programs to end users. Instead of spending hours or literal days transferring software you may or may not have wanted after you received it, you could go to stores or on-line and purchase a plastic disc that contained between 600-700 megabytes of information on it.
The potential of this, in fact, was so strong, that there was an entire industry of providing databases, news summaries, and even all-digital magazines using this format. Booklets of CD-ROMs became resplendent, and libraries could allow patrons to check out these discs to do research with them.
Besides these more institutional compilations, an industry phone number database rose up of companies compiling software, artwork, music and more and selling them to end users. Companies with names like Walnut Creek, Wayzata, Valusoft, and Imagemagic would have catalogs of CD-ROMs to buy. Starting out with software from bulletin board systems and gathered from FTP sites, these CD-ROMs quickly ran out of easy-to-find material to fill, and an era of “shovelware” began, allowing these products to claim “thousands of files, gigabytes of materials” while pulling from more and more out-of-date sources.
As websites, torrents and other means of transport brought the era of physical media for software to a close, the world was left with a finite, contained pile of titles that had come out on CDs. And, as luck would have it, people have been uploading those out of date files to the Internet Archive for years.