Negative/positive is the basic system of most film photography. When film is exposed and developed, the tones are reversed: light areas of the scene appear dark and dark areas appear light. This is the negative. Printing the negative onto light-sensitive paper reverses the tones again and makes a positive image.
The big advantage is that many prints can be made from one negative. William Henry Fox Talbot developed this system in the 1830s and 1840s. His friend Sir John Herschel introduced the terms "negative" and "positive". Herschel also used the word "photography" in 1839 and helped make it the standard term.
Do you have a better definition? Share it in the comments.
