Leftside

Leftside is a term used chiefly as a shorthand reference to the left-hand side of something, especially in mathematics, logic, and computing. When written as left-hand side or left side, it denotes the portion of a binary relation that appears on the left of an equality or inequality, often abbreviated LHS. In mathematics and algebra, the left-hand side of an equation or inequality is the expression preceding the equals sign or inequality symbol; for example, in 3x+2=7, 3x+2 is the left-hand side. The LHS is contrasted with the right-hand side (RHS), which is the part on the other side of the sign. In proofs, transforming the LHS through operations is a common step toward deriving a conclusion.

In computing and programming, left side can refer to the assignment target in an assignment statement or the left operand of an operator, depending on language syntax. For instance, in x = f(y), x is the left-hand side. Some languages also describe left-hand side expressions as assignable, as opposed to right-hand side expressions that yield values but cannot be assigned.

In user interfaces and typography, left side commonly describes the portion of a layout that appears on the left, such as navigation panels or labels, and is used to describe alignment and reading order. Leftside, however, is not a standalone technical term with a single canonical definition beyond its role as a descriptive descriptor for the left portion of a paired relation, expression, or layout, and its meaning is determined by context.