Digital field guides can be accessed on a tablet computer.
The field guide is a kind of reference book, intended to be taken into the field, to assist in the identification of plants and animals. As they are meant to be carried outdoors, they are usually small books rather than large volumes that would be more convenient at home or in the library. Often, they make use of classification and identification systems called keys, by which the exact identity of a specific plant or animal can be determined through observation. A field guide can also be intended for identifying other naturally occurring objects such as gemstones or other minerals and man-made objects such as boats, cars, coins or antiques.
Field guides identify plant and animal species native to a given area.
The first field guides were nothing more than a collection of drawings of plants and animals with descriptions of these subjects. Many of the early field guides featured engravings of drawings and paintings meticulously reproduced by an artist from direct observation. Before the invention of photography, these field guides were often the only tool available for identifying plants and animals. At the beginning of the 21st century, digital field guides began to appear, allowing users to access large volumes of information over the Internet with tablets and smartphones.
The technical depth of a field guide depends on the target audience. Some field guides offer generalized classification tools, grouping subjects loosely. More detailed field guides use identification keys to provide accurate determinations of identity. Identification keys are composed of a series of instructions organized to guide the user through a step-by-step process. Each step has one or more possible choices, the selection of which directs the user to the next step, continuing until identification is reached.
Although the field guide concept was originally conceived as an aid to the identification of natural objects, the scope of this type of book became increasingly broader, especially in the mid-20th century. Specialist field guides aimed at hobbyists and enthusiasts of all kinds began to appear, and today, field guides for all sorts of things are available. Collectible cups, old toys, stamps and wines are just a few examples.
In modern times, field guides to natural objects still often feature drawings in addition to or in place of photographs. The drawings offer a degree of detail and exposure not often captured by a photograph. Field guides for other objects tend to rely more on photographs than illustrations, but this is not absolute. Modern field guides can be broad or specialized, covering, for example, all the birds of North America or just the flowering plants of an isolated island.