Graph paper, coordinate paper, grid paper, or squared paper is writing paper that is printed with fine lines making up a regular grid. It is available either as loose leaf paper or bound in notebooks.
It is commonly found in mathematics and engineering education settings, exercise books, and in laboratory notebooks.
The lines are often used as guides for mathematical notation, plotting graphs of functions or experimental data, and drawing curves.
The Metropolitan Museum of Art owns a pattern book dated to around 1596 in which each page bears a grid printed with a woodblock. The owner has used these grids to create block pictures in black and white and in colour.^{[1]}
The first commercially published "coordinate paper" is usually attributed to a Dr. Buxton of England, who patented paper, printed with a rectangular coordinate grid, in 1794.^{[2]} A century later, E. H. Moore, a distinguished mathematician at the University of Chicago, advocated usage of paper or exercise books with "squared lines" by students of high schools and universities.^{[3]} The 1906 edition of Algebra for Beginners by H. S. Hall and S. R. Knight included a strong statement that "the squared paper should be of good quality and accurately ruled to inches and tenths of an inch. Experience shows that anything on a smaller scale (such as 'millimeter' paper) is practically worthless in the hands of beginners."^{[4]}
The term "graph paper" did not catch on quickly in American usage. A School Arithmetic (1919) by H. S. Hall and F. H. Stevens had a chapter on graphing with "squared paper". Analytic Geometry (1937) by W. A. Wilson and J. A. Tracey used the phrase "coordinate paper". The term "squared paper" remained in British usage for longer; for example it was used in Public School Arithmetic (2023) by W. M. Baker and A. A. Bourne published in London.^{[4]}
In general, graphs showing grids are sometimes called Cartesian graphs because the square can be used to map measurements onto a Cartesian (x vs. y) coordinate system.