Once someone dives into the science of photography they begin to hear a lot of words, such as saturation, that can sound quite confusing.  When used in the context of light, saturation doesn’t mean the same thing it normally does.  

Most people are used to thinking of saturation as the result of absorbing liquid.  A paper towel can quickly get saturated with water or a cotton with ether and so on.  So when we normally think of something as being highly saturated we think of it as being very wet, or having absorbed a lot of something else.

In terms of color and light things work differently. 

A beam of white light contains every color.  Therefore, in terms of light, every color combined equals white.  When an object appears to be white, it is because the object is reflecting every single color towards us.  When an object appears to be the color red is actually absorbing every color except for the red, which it reflects.  At the other extreme is an object that is black.  This is absorbing all of the colors in the white light and reflecting none. 

The term saturation comes into play when measuring the amount of color being reflected.  If an object absorbs every color except blue, for instance, then that blue is considered to be highly saturated.  If,  however, the object absorbs some of the blue along with everything else, then the blue is less saturated. 

When all of this is brought back to the context of photography it can be a little trickier; still, the same basic idea is applied.  A photo with very dull colors is considered to have low saturation.  Further, the more blacks and grays that appear in the photo, the less saturated it is. 

Photographers who deal with film choose their film based partially on its level of saturation.  Some film will have a high saturation while others a low.  A photographer may choose to shoot a portrait with a low saturation so as to bring out the details in the subjects face.  A landscape photographer may want a heavily saturated film because it punches up the colors and the finer details that get lost aren’t as important.

With digital cameras there tends to be a standard of setting a low saturation as a default.  Most cameras will let you adjust that before you take the picture.  People are more likely to play with the saturation of their digital pictures after the shot has been taken though.  Doing so is easy with almost any photo editing software out there.

To get a better idea of what saturation levels actually do to a picture then open up your editing software and play with some of your shots.  If you have a picture that has very bland coloring then increase the saturation and you may be surprised at the result.  Have fun, but pay attention to what you’re doing.  That way you’ll better understand what you’re doing.