An Overview of Memory
Memory is a hardware component in a computer that allows it to store data temporarily. In computers, memory is divided into two categories: primary memory and secondary memory.
Primary memory is where the computer stores its operating system, user applications, and temporary files. Secondary memory is where the computer stores data that the user wants to keep for an extended period of time.
Most laptops have 4 RAM slots because each slot can hold a maximum of 4GB of data. When you install new RAM, the computer automatically recognizes it and registers it in the operating system.
If you try to install more than 4GB of RAM in a laptop, the computer will tell you that you have 4 RAM slots and will ask you which ones you want to use.