Photographs are a physical copy of an image captured either on film or directly to special paper.

Photography dates all the way back to 1824, when the first process called heliography was invented by Nicéphore Niépce, but it was a bit different than what we are familiar with today. His process would take several days of exposure time to make the image. Through many years of innovation and invention, photography evolved to what we are more familiar with today. Color photography as we know it didn't really come into the more modern form until the 1930s.

Improper storage is one of the most common causes of damage. Heat and humidity can drastically cause damage to printed photographs. Of course, most people are familiar with damage over time, even in properly stored photos. Fading and cracking of printed photos are common over time, even when properly stored.

Slides are a transparent media that when light is shown through it, and via some level of magnification, displays the image on a surface for viewing.

Slides in one form or another date all the way back to the 17th century, in what was called a lantern slide (also known as a magic lantern). Lantern slides were a transparent image on glass, and was introduced in 1849. Lantern slides were large compared to today's slides, measuring 3 1/2 x 4", and were fragile since they were on glass. Today, most people are familiar with 35mm slides, which were invented in 1935.

Slides are also vulnerable to heat and humidity, and over time can become brittle and crack, damaging the image.

Negatives, in the form most people are familiar with, are the inverse color image that printed photographs are created from. When a picture is taken, the film is exposed to light to capture the inverse color image that then is developed into the printed photograph.

The current form of negatives was not developed until around the 1930s. Prior to this, a "negative" was actually applied to a plate, and then "developed" into the printed photograph.

Negatives are vulnerable to heat and humidity. Negatives will become brittle and crumble or break easily.