Some people become confused when negative, positive and reversal films are discussed. Following is a simplified explanation, with no understanding of physics or chemistry required, honest.
Negative films are simple to understand.
Where the film is exposed to light, it turns dark after developing. So light objects, photographed on negative film come out dark and dark objects come out light. Also negatives are developed to a low contrast, which means there is less difference between light and dark values in the negative than was present in the scene being photographed. Positive films are so called because they normally have a positive image on them, that is, one that duplicates the original scene. Actually positive film are essentially the same as negative films except that the contrast is higher tocompliment the contrast of the negative.