Random Access Memory (or RAM) is what your computer uses to run programs, in addition to the processor. RAM is mostly used to play games, or run highly detailed programs. RAM is measured in megabytes and gigabytes. The higher the number of MB or GB of RAM your computer has, the better and faster it'll perform.
Some computers (mainly laptops) have a sleep function, that after a certain amount of time, the computer will turn off. In this mode, the RAM is used to store all the information about the programs you're using, so the next time you turn it on (usually by the power button), your computer will reload your last session, just as it was when you left it. The RAM will save whatever you're doing for long periods of time, lasting well over a day.
You can buy more RAM for your computer, however, the manufacturers of your computer will have set a limit on the maximum amount of RAM your computer can have. This can depend on the computer itself, or the operating system it's using. Most modern desktop computers can hold upto 8GB, meanwhile, laptops normally only allow 2 to 3GB to be used. Despite this, it'll depend on what operating system you're using. Here is a little table which shows the maximum amount of RAM each modern operating system can have (even if your manufacture allows more, you'll need to stick to this limit).
Windows XP[]
| Windows XP | RAM Limit |
|---|---|
| Home Edition (32-bit) | 4GB (4096MB) |
| Home Edition (64-bit) | 4GB (4096MB) |
| Professional (32-bit) | 4GB (4096MB) |
| Professional (64-bit) | 4GB (4096MB) |
Windows Vista[]
| Windows Vista | RAM Limit |
|---|---|
| Home Basic (32-bit) | 4GB (4096MB) |
| Home Basic (64-bit) | 8GB (8192MB) |
| Home Premium (32-bit) | 4GB (4096MB) |
| Home Premium (64-bit) | 16GB (16384MB) |
| Business (32-bit) | 4GB (4096MB) |
| Business (64-bit) | 128GB (131702MB) |
| Enterprise (32-bit) | 4GB (4096MB) |
| Enterprise (64-bit) | 128GB (131702MB) |
| Ultimate (32-bit) | 4GB (4096MB) |
| Ultimate (64-bit) | 128GB (131702MB) |
Windows 7[]
| Windows 7 | RAM Limit |
|---|---|
| Home Basic (32-bit) | 4GB (4096MB) |
| Home Basic (64-bit) | 8GB (8192MB) |
| Home Premium (32-bit) | 4GB (4096MB) |
| Home Premium (64-bit) | 16GB (16384MB) |
| Professional (32-bit) | 4GB (4096MB) |
| Professional (64-bit) | 192GB (196608MB) |
| Enterprise (32-bit) | 4GB (4096MB) |
| Enterprise (64-bit) | 192GB (196608MB) |
| Ultimate (32-bit) | 4GB (4096MB) |
| Ultimate (64-bit) | 192GB (196608MB) |