SpanS

Spans are terms used across disciplines to denote a contiguous extent, such as a length, a segment of text, or a period of time. The concept centers on connecting two endpoints.

Historically, a span is the distance from the tip of the thumb to the little finger with the hand spread. It is commonly about 9 inches (23 cm) but varies by culture and era. Spans have appeared in various measurement systems as rough guidelines alongside the cubit or the foot.

In linear algebra, the span of a set of vectors is the collection of all linear combinations of those vectors. It defines the subspace generated by the set and is central to notions of independence and basis.

In text and NLP, a span is a contiguous sequence of characters or tokens. Spans are used to annotate text for tasks such as named entity recognition, coreference, or relation extraction.

In programming, a span often refers to a view of a contiguous sequence of elements rather than a copied copy. For example, languages like .NET offer System.Span<T> as a type for safe slices.

In HTML, the span element is an inline container that groups text or inline elements for styling without introducing line breaks.

In civil engineering, the span is the distance between adjacent supports (for example, between bridge piers). The span length influences load distribution and vibration characteristics.

A time span, or duration, is the length of time between two instants, often measured in seconds, minutes, hours, days, or years.