A set of data points which represent some function, trend, samples, etc.

A component of a graph, such as a label, tick mark, axis, or plot.

The graphical representation of one or more data sets. In PHPlot, each graph contains a single plot, but a plot can contain representation of multiple data sets (for example, you can have 3 line charts on a plot).

Less formally, the term 'plot' is often used for the overall output of PHPlot: an image with a complete graphical representation of data, with labels, legend, title, etc.

A complete, labeled, graphical representation of some data sets. In PHPlot, a graph contains a single plot and other elements such as axes, tick marks, and labels.

A graphical image, represented as data. For example, a PNG file is an image in PNG format which is stored in a file. PHPlot creates images using the GD library. A PHPlot image contains one or more graphs (but usually only one).

The coordinate space of the plotted data. This is the "real world" coordinate space, in the units of whatever the plotted data measures. The origin of the world coordinate space is the 0,0 point on the X and Y axes.

The coordinate space used by GD to create images. The origin is at the upper left corner, X increases to the left, Y increases down, and the units are pixels. Also known as Pixel Coordinates or GD Coordinates.

A programming library used to create and manipulate images. GD can be found at the GD Graphics Library home page. You can think of GD as a software implementation of a video card. GD is also available as a PHP extension, and that is what PHPlot uses to create images.