Photography covers many distinct areas. Much of it is purely amateur, the sort of holiday snaps and informal shots of family and friends we all enjoy. It is also an art form in its own right. Videos and stills are now commonplace in galleries as art installations. Commercial photography is another important area, and this includes things like photojournalism, wildlife photography, advertising and pornography, to name but a few. In science, photos are used to help predict weather patterns, to observe the universe and in spectroscopy, a practice that has numerous applications, such as looking for toxins in blood samples.