In other multicellular organisms, the word "embryo" can be used more broadly to any early developmental or life cycle stage prior to birth or hatching.

"growing in",[2] from ἐν (en), "in"[3] and βρύω (bruō), "swell, be full";[4] the proper Latinized form of the Greek term would be embryum.

In animals, fertilization begins the process of embryonic development with the creation of a zygote, a single cell resulting from the fusion of gametes (e.g. egg and sperm).

[5] The development of a zygote into a multicellular embryo proceeds through a series of recognizable stages, often divided into cleavage, blastula, gastrulation, and organogenesis.

[15][16] Many visible changes in embryonic structure happen throughout gastrulation as the cells that make up the different germ layers migrate and cause the previously round embryo to fold or invaginate into a cup-like appearance.

[8] Past gastrulation, an embryo continues to develop into a mature multicellular organism by forming structures necessary for life outside of the womb or egg.

[22] The plant embryo cells continue to divide and progress through developmental stages named for their general appearance: globular, heart, and torpedo.

Meristems (centers of stem cell activity) develop during the torpedo stage, and will eventually produce many of the mature tissues of the adult plant throughout its life.

[38] Creating and/or manipulating embryos via assisted reproductive technology (ART) is used for addressing fertility concerns in humans and other animals, and for selective breeding in agricultural species.

Between the years 1987 and 2015, ART techniques including in vitro fertilization (IVF) were responsible for an estimated one million human births in the United States alone.

[40] Some have proposed (or even attempted - see He Jiankui affair) genetic editing of human embryos via CRISPR-Cas9 as a potential avenue for preventing disease;[41] however, this has been met with widespread condemnation from the scientific community.

[42][43] ART techniques are also used to improve the profitability of agricultural animal species such as cows and pigs by enabling selective breeding for desired traits and/or to increase numbers of offspring.

[45] IVF and other ART techniques, including cloning via interspecies somatic cell nuclear transfer (iSCNT),[46] are also used in attempts to increase the numbers of endangered or vulnerable species, such as Northern white rhinos,[47] cheetahs,[48] and sturgeons.

[49] Cryoconservation of genetic resources involves collecting and storing the reproductive materials, such as embryos, seeds, or gametes, from animal or plant species at low temperatures in order to preserve them for future use.

[55] The Svalbard Global Seed Vault in Norway maintains the largest collection of plant reproductive tissue, with more than a million samples stored at −18 °C (0 °F).