The "carpet" plot is a form of graph which illustrates the behaviour of a function of two independent variables. Unlike the conventional type of graph, which shows the variation of a function with one of the independent variables while the other is held at a series of fixed values, the carpet plot shows how the function varies with both variables together. This feature facilitates interpolation of the function for intermediate values of both independent variables. This Item illustrates the problems that can arise with conventional 2-dimensional plots and shows how these are overcome by use of carpet plots. It provides examples of carpet plots to illustrate the various forms they may take. The concept of the carpet plot is extended to the "lattice" plot which can represent the behaviour of a function of three independent variables. Examples of lattices are given to show how they may be constructed and how they are used to interpolate between values of all three variables.