nesting

Nesting refers to the act of placing items within one another or to the state of being nested. It covers natural processes, such as a bird building a shelter for its eggs, and human-made systems where components or ideas are embedded within larger structures.

In biology, nesting describes how animals prepare and use a shelter for reproduction and rearing young. Bird nests vary widely, from ground scrapes to elaborate woven structures. Nesting behavior is shaped by ecology, predation, and resource availability, and may involve incubation, brooding, or seasonal reuse.

Humans frequently reference nesting in household organization or pregnancy, where a nesting instinct is described as a drive to arrange the home or prepare for a newborn. Artificial nesting aids include birdhouses and nest boxes, sometimes designed to attract particular species or support urban wildlife.

In computing, nesting refers to placing data or constructs inside similar structures. Examples include nested lists or arrays, nested loops, and nested functions. In markup and data formats, elements or objects can be nested to represent hierarchical relationships, as in HTML, JSON, or XML.

Nesting also appears in design and manufacturing, where shapes are arranged to fit within others to reduce material waste. The term is used in crafts, such as nesting dolls (matryoshka), where smaller pieces fit completely inside larger ones.