This paper points out the reasons for using good slides for illustrating technical papers. It mentions some of the faults in slide preparation and projection. A number of suggestions are given for the preparation of improved slides, with detailed instructions on graphs, bar charts, and tables. The use of color for improving technical slides is discussed, and a comparison is made between the standard 3-1/4 × 4-inch and the smaller 2 × 2-inch slides. Finally a few suggestions are offered for the improvement of slide presentations.