StartupSound is a global option that specifies whether Mathematica plays a sound when it is launched.
SubscriptBox[x, y] is the low-level box representation for x_y in notebook expressions.
SuperscriptBox[x, y] is the low-level box representation for x^y in notebook expressions.
TableDepth is an option for TableForm and MatrixForm which specifies the maximum number of levels to be printed in tabular or matrix format.
ToUpperCase[string] yields a string in which all letters have been converted to uppercase.
Write
(Built-in Mathematica Symbol) Write[channel, expr_1, expr_2, ...] writes the expressions expr_i in sequence, followed by a newline, to the specified output channel.
$Canceled is a symbol returned when notebook input is canceled, for example from a dialog box.
$ConfiguredKernels is the default list of kernels that are configured to be launched for parallel computing.
$ContextPath is a global variable that gives a list of contexts, after $Context, to search in trying to find a symbol that has been entered.
$KernelID is a unique ID number assigned to each running parallel kernel.