Why main memory is faster than secondary memory?

Why computers main memory is faster than secondary memory?

There are almost as many variations as there digital devices on the market but generally, main memory (RAM) is internal to the device and will access data through parallel circuitry at the clock speed of the cpu. For example a 32 bit machine reads 32 bits at once. Secondary memory (hard drives, flash drives etc) is dependent on mechanical functions and some move the data via serial means (1 bit at a time).

Primary memory is faster to access because it is wired directly to the processor. It is used by the system to perform operations while programs are running. For more info visit here: http://www.bethmooreblog.com/