Graphics[primitives, options] represents a two-dimensional graphical image.
BoxFrame is an option for FrameBox objects that specifies whether to draw a frame around the contents of the box.
CellProlog is an option to Cell that gives an expression to evaluate before each ordinary evaluation of the contents of the cell.
FractionLine is an option for fractions that specifies the thickness of the line separating the numerator and denominator.
GridDefaultElement is an option for the low-level function GridBox that specifies what to insert when a new element is created interactively in a GridBox.
ScreenStyleEnvironment is an option for notebooks that specifies the style environment to be used in displaying a notebook on the screen.
TabFilling is an option for character selections that specifies how a Tab character is represented on the screen.
WriteString[channel, expr_1, expr_2, ...] converts the expr_i to strings, and then writes them in sequence to the specified output channel.
$SessionID is a number set up to be unique to a particular Mathematica session.
SmoothHistogram[{x_1, x_2, ...}] plots a smooth kernel histogram of the values x_i.SmoothHistogram[{x_1, x_2, ...}, espec] plots a smooth kernel histogram with estimator ...