Cache Memory

I know a little bit about Main Memory you have DRAM Chips and SDRAM Chips.

DRAM Chips need to be Re Charged every Few ms to Hold the Bits in the Capacitor?
Do I have this Right?

SDRAM Chips do not need to be Re Charged every Few ms as long as the Power Supply is On?
Do I have this Right?
And I thought DRAM and SDRAM both need to be Re Charged?

SRAM does not use Capacitors but Transistor MOSFETs.
But Transistors just Turn On and Off they do not Hold a Charge.
So how can it Hold Bits that...

Cache Memory