The animal on the cover of Windows Vista Pocket Reference is a European common frog (Rana temporaria), also known as the "brown frog" or "grass frog." This species inhabits Europe from the Pyrenees to the Urals and West Siberia. It can be found in just about any damp habitat within this range, including lowland and mountain forests, meadows, swamps, ponds, lakes, rivers, gardens, backyards, and parks.

The European common frog has a small, squat body and a wide, flat head. The frog is typically brown or grayish in color but can also have yellowish or red hues. The lower segments of its backbone are fused into a stiff rod called the urostyle, which, along with its strong pelvic bones, helps provide strength and firmness to the rear of the body. The frogs have powerful hind legs and webbed feet, which contribute to their excellent jumping and swimming abilities.

The males of the species tend to be slightly smaller than the females and are identifiable by whitish swellings on the inner digits of their front feet. During breeding season, these swellings support dark "nuptial pads" that enable the male to grasp the female more effectively. The male can be very vocal when trying to attract a mate, even croaking underwater. Once he has attracted a female, he climbs on her back and embraces her in a tight, sometimes suffocating grip called amplexus, which can last up to two days. He fertilizes the eggs as the female lays them. In recent years, scientists researching the species in the Pyrenees have discovered a behavior known as "clutch piracy," in which gangs of males search for newly laid eggs to fertilize them again. The researchers have found evidence of fertilization from as many as four males in a single clutch of eggs.

Although huge numbers of eggs are laid, few frogs survive to adulthood. Tadpoles are preyed upon by both terrestrial and aquatic animals, and adult frogs count grass snakes, kingfishers, and herons among their many predators. Additionally, many frogs are caught by humans for the purposes of education, medicine, and science. Overall, however, this particular species is neither declining nor threatened.

The cover image is from Wood's Reptiles, Fishes, Insects, &c. The cover font is Adobe ITC Garamond. The text font is Linotype Birka; the heading font is Adobe Myriad Condensed; and the code font is LucasFont's TheSans Mono Condensed.