What is RAM(Random Access Memory)?
RAM, which stands for Random Access Memory is where the computer stores and retrieve data. This is know as volatile memory and what that means is that the computer will temporarily store data in the memory slots that ram has, for example a program that you have opened and running. this needs power to keep data stored in these memory modules, so if you turn of your computer, the data inside the memory will be lost. there are many different types of ram for example the latest that they have made are called DDR4. there are DDR3 and DDR2, so make sure that you get the appropiate type of ram that is compatible with the motherboard that you have.
Corsair Vengance LPX (8gb)
I will chose the Corsair Vengance LPX for this build, with 8gb you can do multiple stuff and it is sufficient enough for just a home use computer. now if you are planning to make a gaming computer you might have to buy another stick of 8gb to run the game well enough.