Latent Image
The invisible record formed in an emulsion by exposure, before development makes it visible.
In depth
The latent image consists of microscopic clusters of metallic silver too small to see or measure directly, yet stable enough to survive for years before processing. Its existence is what separates photography from earlier direct-printing processes: exposure times fell from hours to fractions of a second because the image no longer had to be built to visibility by light alone.
Examples in practice
A roll exposed on holiday and developed two years later still yields printable negatives from its latent image.