In the previous lesson, we used some values such as 242 or 'James Knight'. These types of values are referred to as constant because we certainly know them before their use and we don't change them in our statements.
If you intend to use a certain category of value over and over again, you can reserve a section of memory for that value. This allows you to put the value in an area of the computer's memory, easily change the value for another, over and over.
To use the same area of memory to store and remove values as needed, the SQL interpreter needs two primary pieces of information: a name and the desired amount of space in memory capable of storing the value.
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