RAM

We're talking about computer RAM, not the animal and not the truck. RAM = Random Access Memory. Manu people confuse RAM (also called memory) and hard-drive space.
 
Memory in computers is a lot like memory in people. That's where it got its name. It refers to how much information the computer can hold readily available without having to go look it up on the hard-drive. When you open a program your computer loads the instructions for running that program into its memory. When you create a document, it stores the contents in its memory until you save it permamnently. When you close the program, the computer clears the memory to make room for something else. That's why you can lose a document if you forget to save it or your lose power and the document has not been written to the hard drive yet.
 
An "out of Memory" message doesn't mean your hard drive (storage) is full — it means your computer doesn't have any more room to store information about open programs and documents. Close some programs or documents to free up some RAM.