Dimension

A dimension is the measure of the size of something.

For example, the three dimensions that give the size of an object in the world are

1. length
2. width
3. height

Dimensions can be used to measure position too. The distance to the position from the starting place can be measured in the length, width and height directions. These distances are the measure of the position.

Sometimes the fourth dimension, time, is used to show the position of an event in time and space.

Other Dimensions

In modern science, people use other dimensions.

Dimensions like temperature and weight can be used to show the position of something in less simple spaces.

Dimensions in mathematics

Mathematicians also use dimensions. In mathematics, dimensions are more general. Dimensions in mathematics might not measure things in the world. The rules for doing arithmetic with dimensions in mathematics might be different than usual arithmetic rules.

Dimensions and vectors

Vectors are used to show distances and directions. Vectors are often used in engineering and science, and sometimes in mathematics.

A vector is the list of numbers. There is one number for each dimension. There are arithmetic rules for vectors.

For example, if Jane wants to know the position of Sally, Sally can give Jane the vector to show the position. If Jane and Sally are in the world, are are three dimensions. Therefore, Sally gives Jane the list of three numbers to show her position. The three numbers in the vector Sally gives Jane might be:

1. Sally's distance north of Jane
2. Sally's distance east of Jane
3. Sally's height above the earth