Before we start looking at code, we need to understand, in some detail, how data is represented on a computer. The common cliché is that all data in a computer is in ones and zeroes. This is true, but not so important when we talk about memory management. Instead, we are concerned about where the data is stored. All computers, whether a desktop, laptop, tablet, or phone, store data in two places.

The first place we normally think of is the filesystem. It is stored in a dedicated piece of hardware. In many computers, this is called a hard disk drive, but more recently, some computers have started to use solid state drives. The other thing we hear about while buying computers is the amount of memory it has. Computer memory comes in "sticks", which are much smaller than normal drives. All data, even if it is primarily stored on the Internet somewhere, must be loaded into the memory so that we can interact with it.

Let's take a look at what this means for us programmers...