An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg (Latin, ovum) is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing embryo can survive on its own. The term "egg" is restricted to the animal kingdom, similar reproductive structures in other kingdoms are termed spores, or (in spermatophytes) seeds, see ovum.
Oviparous animals are animals that lay eggs, with little or no other development within the mother. The study or collecting of eggs, particularly bird eggs, is called oology.
Reptile eggs, bird eggs, and monotreme eggs, which are laid out of water, are surrounded by a protective shell, either flexible or inflexible. The special membranes that support these eggs are traits of all amniotes, including mammals.
Eggs laid on land or in nests are usually kept within a favourable temperature range (warm) while the embryo grows. When the embryo is adequately developed it breaks out of the egg's shell. This breaking out is known as hatching. Baby animals which have just hatched are hatchlings, though standard names for babies of particular species continue to apply, such as chick for a baby chicken. Some embryos have a temporary egg tooth with which to crack, pip, or break the eggshell or covering.
In photography and optics, vignetting ( /vɪnˈjɛtɪŋ/; French: "vignette") is a reduction of an image's brightness or saturation at the periphery compared to the image center. The word vignette, from the same root as vine, originally referred to a decorative border in a book. Later, the word came to be used for a photographic portrait which is clear in the center, and fades off at the edges. A similar effect occurs when filming projected images or movies off a projection screen. The resulting so-called "hotspot" effect defines a cheap home-movie look where no proper telecine is used.