yes, it is an external as well as an internal 
memory.because it is used to store temporary files,so it 
works as voletile memory.and according to our need we can 
also increase number of RAM cards in our computer system.it 
means we can increase efficiency of our computer's memory.

YES

tell you what mate how about try and spell memory correctly in your original question? i have never seen a more stupid forum in my whole life. 

please tell me not all yanks are this stupid.

No RAM is purely an Internal Memory.
Meaning - RAM is also called as System Memory which is used 
to hold the temperary data on it. If the user didn't decide 
to save this temp data, the RAM will flush it. 
Similary, if the temp. data is saved. It is saved on the 
Hard disk like memory. 
Let me explain it by an example.
I've opened a new Notepad file.
I've typed 10 lines of data on the Notepad.
I've neither saved or closed the Notepad file.
I left the PC and came back after 12 hours.
I see the same Notepad file on the PC.
Though it is not saved it shows those 10 lines.
How, is it possible?
It's simple.
when there is something created, edited it would be stored 
on the RAM as the temp. file until it is saved on the PC. 
Once it is saved. RAM's free's that data as it is saved on 
the PC.

So, RAM is a pure Internal Memory.