What do you understand by SRAM & DRAM?

SRAM (Static RAM): The data is SRAM is stored based upon the state of the flip-flop used in the memory architecture, irrespective of the gate implemented. When compared to the other type of RAM, SRAM is more costly. 

But its advantage lies in its power consumption and speed. This type of RAM needs not to refresh the content of the memory call. Due to its faster performance, SRAM is generally used in the manufacturing of cache memory. This type of RAM uses only transistors to store the data.

DRAM:  Dynamic RAM. The name itself suggests that the RAM is dynamic. The concept of Dynamic in the storage mechanism of the memory. The data in this memory is to be refreshed frequently. The reason behind this refreshing concept is the usage of capacitor along with the transistors.