Digital field guides can be accessed on a tablet.
The field guide is a kind of reference book, intended to be taken into the field, to aid in the identification of plants and animals. Since they are made to be carried outdoors, they are usually small books rather than large volumes that would be more convenient at home or in the library. They often 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 may also be intended to identify other natural objects, such as gemstones or other minerals, and man-made objects, such as ships, cars, coins, or antiques.
Field guides identify the 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 topics. Many 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 used to be the only tool available to identify plants and animals. At the beginning of the 21st century, digital field guides began to appear, allowing users to access large volumes of information through 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, loosely grouping topics. More detailed field guides use identification keys to provide accurate determinations of identity. Identification keys are made up of a series of instructions organized to guide the user through a step-by-step process. Each step has one or more possible options, 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 broad, especially in the middle of the 20th century. Specialized field guides aimed at hobbyists and enthusiasts of all kinds began to appear, and today field guides are available for all kinds of things. Collectible glasses, vintage toys, stamps and wines are just a few examples.
In modern times, field guides to natural objects still feature drawings in addition to or instead of photographs. The drawings offer a degree of detail and exposure that a photograph does not usually capture. Field guides for other objects tend to be based 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.