GraphDifference[g_1, g_2] gives the graph difference of the graphs g_1 and g_2.
GraphDisjointUnion[g_1, g_2] gives the graph disjoint union of the graphs g_1 and g_2.GraphDisjointUnion[g_1, g_2, ...] gives the disjoint union of g_1, g_2, ....
GridLinesStyle is an option for 2D graphics functions that specifies how grid lines should be rendered.
HelpBrowserSettings -> {opt_1 -> val_1, opt_2 -> val_2, ...} is a global option that specifies settings for the legacy Help Browser.
HoldForm[expr] prints as the expression expr, with expr maintained in an unevaluated form.
ImageDifference[image_1, image_2] gives an image in which each pixel is the absolute difference of the corresponding pixels in image_1 and image_2.
ImageRegion is an option for cells that specifies the size and position of the bounding box within which a graphic is rendered.
ImageSubtract[image, x] subtracts a constant amount x from each channel value in image.ImageSubtract[image_1, image_2] gives an image in which each pixel is obtained by ...
IncludeConstantBasis is an option for LinearModelFit and other fitting functions that specifies whether a constant term should be included if not explicitly given in the list ...
x++ increases the value of x by 1, returning the old value of x.