What is RAM?.

RAM (Random Access Memory): RAM is Basic Memory of Computer .It is Store Data Temporarily, it store Data until Computer is turn off .it Computer is Turn off the data is erase automatically from the RAM. There are many types of RAM. It is also known as Volatile Memory.
 
i. FPM RAM (Fast Page Mode)
ii. SRAM (Static) it is stores data till the power is switched off. It is not require refresh because transistor use each memory cell. It faster than DRAM.
 iii. DRAM (Dynamic) it is stores data few milliseconds .it is require refresh because use transistor and capacitor for each memory cell.
 iv. VRAM (Video)
 v. EDO RAM (Extended data out) 
vi. SD RAM (Synchronous Dynamic )
 vii. RD RAM (Rambus Dynamic ) 
viii. DDR SD RAM  (Double data rate) 
ix. DDR2 RAM
 x. DDR3 RAM  
xi. DDR4 RAM