plusstegn

Plusstegn, or plus sign, is the symbol '+' used to indicate addition and to denote positive quantities. In mathematics, science, computing and everyday notation, it functions as the binary operator for addition and, when placed before a number, as a unary indicator of positivity. The term plusstegn is used in Danish and Norwegian; Swedish uses plustecken.

The earliest known use of a dedicated symbol for addition is attributed to the late 15th century mathematician Johannes Widmann, who included a + sign in his arithmetic treatises alongside a minus sign. Over the following centuries, the plus sign spread across Europe with the growth of algebra and printed books. Its precise origin remains uncertain, and some theories point to a stylized ligature or a simple cross-like flourish rather than a single source.

In arithmetic, the plus sign denotes addition; in algebra, it is used as a binary operator and as a unary plus for positive numbers. In programming languages, it commonly represents addition; it can also concatenate strings in languages such as JavaScript, Java, and Python. In data transmission and encoding, the plus has special meaning in application/x-www-form-urlencoded, where it represents a space and must be escaped to indicate an actual plus.

Typographically, the plus sign is a cross formed by a vertical and horizontal stroke and appears in many typefaces with minor stylistic variations. In computing, its Unicode code point is U+002B and its ASCII value is 43. On most keyboards it is accessed by holding Shift and pressing the key immediately to the right of the zero key.