As people advance in technology, many of the older technology are in danger of disappearing, particularly as no companies produce them, no research organizations study them, and nobody cares to spend time on them. While people discover or invent technology, there still needs people to study them, and improve or keep them updated. Therefore, it's important to list disappearing technology, so they do not disappear completely, and there is a record for what came before:
1. DVD/CD-ROM - popular in the 1990s and 2000s, it's largely replaced by online downloading, viewing and streaming services
2. Floppy Disk and Disk Drive - important when computer first came onto the consumer market in the mid-1990s, and around year 2000, the floppy disk has been superceded by burning CDs, and then USB drives.
If you guys have any more to list and mention, please do so here. Thank you for reading.