ChetOS.net

Just beat me to it.  On Aug 17, 1982, Philips released the first CD.  Back when the largest consumer harddrive were tens of megs, and most computers barely had 512KB of RAM, this disc could hold an incredible 640MB... that was probably enough to hold all the data on all the floppy discs of everyone you knew.

I wasn't alive when they were first released, but do remember when they started using them for computers.  The librarian showed us one of these new fangled things that held the Encarta Encyclopedia when I was in 4th grade.

Also, a few of my rich classmates had portable CD players that they took with them on field trips.

From cassette to CD to solid state storage (which could hold hundreds of CDs), we sure have come a long way in reliably storage large amounts of information.