I was over at a friend's house recently when we discussed 78 rpm records. He had some recordings that his grandmother had once owned of various Italian operas.
Growing up I obviously had a lot of experience with 33 rpm records and also had a few 45 singles, although they were mostly going by the wayside by the time I started collecting music. I had no experience at all with 78 rpm records.
These 78 rpm records were in mono. I didn't realize how short the records were - less than 3 minutes per side. This probably is obvious to an engineer (78 rpm spins faster than 33 rpm) but less so to an accountant.
The records were made of shellac and apparently they broke very easily. Now the records are in good hands so that isn't as much of a worry. You can see the ubiquitous "discwasher" record cleaner (for dust) alongside the record player; I remember diligently cleaning my albums each time on the turntable.
Wikipedia had a good history of 78 rpm records here (in their general record section). The records lost popularity in the US in the 1950's and became basically extinct in by 1960. It is interesting to me that a modern record player still has a 78 rpm setting given that this format essentially died out 60 years ago.
Another friend said that he remembered children's' albums being in 78 rpm format but that was before my time. Someday maybe someone will pull out an old cassette player and put in my cassettes (mix tapes) for ancient nostalgia's take, too.