Adding Memory commonly known as RAM (Random Access Memory) is often the cheapest and easiest way to improve the performance of your PC or laptop.
The speed improvement is created because the additional memory provides a more space for the system to store information before writing or reading it from the hard drive and allows larger parts of programs to run in memory.
With out sufficient RAM memory the computer has to swap out data onto the hard disk and read write access times to the disk cause a delay which will make the computer response times slower.
Volatile memory RAM can be SRAM or DRAM and is computer memory that requires power to maintain the stored information.
SRAM static ram all data is lost when power is removed.
DRAM dynamic ram allows data to be leaked and disappear automatically without a refreshing.