RAM (Random Access Memory) is the short term memory for a computer or electronic device. When a program is loaded, information is taken from the hard drive and placed into the computer's memory so that it is ready for the processor to work with.
Most computers have 2-4 RAM slots, and each computer accepts a specific type of RAM based on the slot size and other characteristics. Sometimes computer memory cards are referred to as sticks because their shape is similar to a stick of gum: long, flat, and thin. Each stick of RAM has a different, and ever increasing, measurement of how much memory it can store. It wasn't too long ago that RAM could only hold a few MB, but today, it's common for RAM to hold several GB.
Regardless of the specific amount of memory each stick can hold, it is usually less than the total capacity of the computer's hard drive (except in cases where the computer does not have a hard drive though those specific cases are beyond the scope of this article), and more than the memory connected directly to the computer's processor (often referred as CPU cache or L2 cache). RAM is much far faster than the typical hard drive but slower than the CPU cache.
When the computer is turned off, all of the data stored inside RAM is erased, which is why computers have hard drives - for permanent storage even though they're many times slower than the computer's memory.
In certain cases, the quickest and cheapest way to increase the overall speed of a computer is to add more memory. If the sum of the memory required by all of the programs that are currently running on the computer exceed the total amount of available RAM, the computer will start to "swap" memory, which means it will move some of the data to and from the hard drive. This is a time consuming process and is eliminated by either closing down enough programs so the computer needs less RAM for the moment, or by adding additional memory to the computer. If a program is simply installed, but not running, it is not loaded into memory and therefore does not affect the amount of RAM needed.
Sometimes programs have what is known as a memory leak. Internet Explorer and Firefox are notorious for various memory leaks. On Windows, check your task manager or on Linux and Macs, check your system monitor, top, or ps to see which programs are loaded into RAM. If the amount of RAM is much higher than when you first loaded the program, chances are this is the case. Simply restarting the program can be a temporary fix especially if it takes several hours to notice the slowdown. In these cases, make sure you have the latest version in case the issue has been fixed, and make sure your software vendor is aware of the problem.
