Chemigrams are abstract photographic patterns created through chemical manipulation of light-sensitive paper. Pierre Cordier discovered the process in 1956 when he found that certain resists could block the chemical effects of developer and fixer, leaving patterns. The document provides instructions for creating positive and negative chemigrams using developer, fixer, and light exposure to produce images. It encourages experimenting with different papers, chemicals, and resists to create varied effects outside of the traditional darkroom process.