The word graph is used in two quite different ways in mathematics. Firstly there is a technical use where graph refers to a collection of points (nodes) connected by line segments or arcs. Graph theory is the study of the properties of such objects, and this is a very interesting branch of mathematics, first appearing in connection with Euler’s bridge problem (Photo #33). Then the word graph can also carry the idea of a chart: a pictorial way of representing or conveying information. Common types of chart are pie graph, bar graph, linear graph and histogram. Examples of both types of graph can be seen in our photograph.
