RAM stands for Random Access Memory.
RAM is a temporary memory. The computer uses it to store data and instructions while it is working. When the computer is switched off this information is lost. RAM is plugged into the motherboard and looks like a card shown on the right.
The capacity of RAM in a computer can be increased based on the user requirements. The maximum increase depends on the motherboard. It depends on the number of available slots on the motherboard and the maximum capacity each slot can support. The Clock Speed RAM also plays an important role. The frequency has to match with the motherboard's frequency.