Variables are letters than stand for numerical values.
The most important thing to remember about variables is that they are dynamic and their values can and do change depending on what is being done to them.
For instance [x = 2y] means that if [x] increases by a factor of two, then [y] will increase by a factor of four.
Likewise, if [x] is increased by a factor of four, then [y] will increase by a factor of sixteen.
This relationship, for example, demonstrates the relationship called a square and many features of the world, such as the curvature of space and time in large quantities, have this relationship.
As the distance of an object increases by a factor of two from another object, the space and time curvature relative to that object decreases not by a factor of two, but by a factor of four.
Typically, in mathematics:
[x] stands for common values in simple algebra and for the horizontal plane in geometry.
[y] is often used for the second variable in simple algebra or in more complex algebra in which a second variable exists.
[z] is often used to show the third dimension in a coordinate plane and represents, essentially, the distance into the third dimension.
[p] and [q] are used in logic to represent propositions or sentences.
In computer science, variables are extremely important as they can hold more than just simple numerical values but also memory addresses and characters as well as strings of characters and multi-dimensional lists or arrays of values.
