CD-ROM
The data variant of the audio CD, specified by Sony and Philips in 1985 in the "Yellow Book". 650 MB on a disc when hard drives were measured in tens of megabytes — it changed what software could be.
The ISO 9660 filesystem made discs readable on every platform, with the infamous filename restrictions that the Joliet and Rock Ridge extensions later relaxed. Speed is quoted in multiples of the audio CD's 150 kB/s, so a 52× drive barely reaches 8 MB/s. Capacity rose to 700 MB, and recordable CD-R and rewritable CD-RW followed. The impact on the industry was large: multimedia encyclopedias, games with video sequences, Linux distributions on one disc instead of thirty floppies, and software installation without downloading. Replaced by DVD, then USB sticks, and finally by everything being fetched over the network.