The rings are mostly made of water ice and the total mass is about that of the moon Enceladus. The mass is different for the three big rings and the theory is they probably formed at different times. All the various features (gaps, ripples) can be explained by the gravity of moons passing by and through the rings. I didn't realize that the rings are particularly interesting to study because the behave the same as the arms of spiral galaxies.
The way that moons keeps a gap in the rings open is similar to how planets form from dust rings.
The moon Enceladus is about size of Great Britain. It has a smooth surface so it's thought not to be old, but detailed images show lots of fractures, so there are tectonic forces in the crust. Giant plumes of dust are being ejected from geysers and form a newly discovered E ring. It's made mostly of water vapor and hydrocarbons and with the warmth (geysers) it is perhaps a location where pre-biotic life could form, though Cassini doesn't have the instruments to search for any.
Cassini is the size of a school bus. Even though it was launched on a huge rocket it needed several flybys of the venus and earth to build up speed to get to Saturn in only 7 years. Half its weight was fuel used to slow down its acceleration so it could be captured by Saturn's gravity.
Saturn is 10 times as far from the sun as the earth is, so sunlight is 100x dimmer (square of the distance). Solar power wouldn't be enough for it so it uses a plutonium power plant. If you were there Saturn would be a lot dimmer than the photos and you wouldn't see all the rings. Cassini uses long exposures to get bright pictures. Think of looking at a red car at night, how sharp is the color? Cassini uses Titan to do orbit changes and also some remaining fuel for rockets and a gyroscope for orientation.
She showed a lot of great images which you can see in the presentation below and at
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