yaxis

The y-axis, also referred to as the vertical axis in a two-dimensional Cartesian coordinate system, is the axis that typically represents the dependent variable. It intersects the x-axis at the origin (0,0). In standard mathematical convention, y increases upward, and values above the origin are positive.

In data visualization and plotting, the y-axis conveys the magnitude of a quantity as a function of the horizontal variable x. The axis is labeled with a symbol (often y) and a unit. Tick marks and gridlines aid interpretation; the axis can be scaled linearly or logarithmically, and ranges may be set automatically or manually.

In computer graphics and screen coordinates, the vertical axis is sometimes inverted, with y values increasing downward from the top of the display. This convention is common in image processing and user interface frameworks, and requires transformation to match standard mathematical orientation.

For charts that compare multiple series, a single y-axis is common; some charts use dual or multiple y-axes to accommodate different units, with care to prevent misinterpretation.

In software libraries, yaxis may refer to a configuration object or property that controls the vertical axis—its title, range, tick format, and whether to show gridlines. The term is used across plotting and visualization tools, reflecting the central role of the vertical axis in illustrating relationships between variables.