Path
(Built-in Mathematica Symbol) Path is an option for Get and related functions which gives a list of directories to search in attempting to find an external file.
RowAlignments is an option for the low-level function GridBox that specifies how entries in each row should be aligned.
ShowClosedCellArea is an option for cells that specifies whether a rectangular bar is displayed next to a closed cell group to indicate the number of cells in the group.
SpanCharacterRounding is an option for selections that specifies the method used for rounding a spanning character when its size is to be adjusted.
StyleMenuListing is an option for cells that specifies whether a given cell style is listed in the Format \[FilledRightTriangle] Style submenu.
$Context is a global variable that gives the current context.
$Packages gives a list of the contexts corresponding to all packages which have been loaded in your current Mathematica session.
$PerformanceGoal gives the default setting for the option PerformanceGoal for graphics and other algorithmic functions.
Product
(Built-in Mathematica Symbol) Product[f, {i, i_max}] evaluates the product \[Product]i = 1 i_max f. Product[f, {i, i_min, i_max}] starts with i = i_min. Product[f, {i, i_min, i_max, di}] uses steps di. ...
Abs
(Built-in Mathematica Symbol) Abs[z] gives the absolute value of the real or complex number z.