"Fold (S. 57, T. & G. 57)" is a screenprint in colours by British Op artist Bridget Riley, created on the high quality Fabriano paper and presented with full margins. The work exemplifies Riley's characteristic exploration of optical illusion and spatial perception through carefully controlled colour and geometric form. The title's reference to "fold" suggests the artist's investigation of how planes of colour can create the illusion of dimensionality and movement on a flat surface.