A column describes a way in which objects, such as numbers, can be arranged. Columns are commonly used alongside rows in an array, such as a table. They are the vertical counterpart to the horizontal row.
The objects contained within a column, in the context of mathematics, is usually a number or expression. Matrices are one area of mathematics in which columns are commonly used, though the topic is outside the scope of primary math. Matrices are organized in a similar way as a table. Below is an example of a 3×3 matrix, where "3×3" refers to the matrix having 3 rows and 3 columns.
In this matrix, the first column contains the numbers 1, 7, and 8. The second column contains the numbers 3, 4, and 6, and the third contains 2, 12, and 8. Columns are usually read from left to right, while rows are read from top to bottom. So column 1 would contain 1, 7 and 8, while column 3 contains 2, 12, and 8.
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Columns are used in many other contexts, not just arrays and mathematics. In architecture and engineering, columns are vertical elements that bear the weight of a structure above and transmit it to elements below. The following figure is an example of Greek architecture, where columns were often prominently displayed.
A column is also a military formation in which soldiers march in one or more lines such that the column length is much longer than the width. For example, there could be 2 or 3 lines of 100 soldiers.
Newspapers, magazines, and other types of publications often organize text in such a way where they form multiple columns. The term "column" in such publications usually refers to a relatively small, recurring section of the publication written by the same person, where they express an opinion.