Masking is an option for various image analysis and processing functions that specifies on which regions they should operate.

RateOfChange

VolumeRateOfChange

CellGroupData[{cell_1, cell_2, ...}] is a low-level construct that represents an open group of cells in a notebook. CellGroupData[{cell_1, cell_2, ...}, 1] represents a cell ...

NotebookDirectory[] gives the directory of the current evaluation notebook. NotebookDirectory[nb] gives the directory for the notebook specified by nb.

PlotRangeClipping is an option for graphics functions that specifies whether graphics objects should be clipped at the edge of the region defined by PlotRange, or should be ...

Stack[] shows the current evaluation stack, giving a list of the tags associated with evaluations that are currently being done. Stack[pattern] gives a list of expressions ...

BellY[n, k, {x_1, ..., x n - k + 1}] gives the partial Bell polynomial Y n, k (x_1, ..., x n - k + 1). BellY[n, k, m] gives the generalized partial Bell polynomial of a ...

Hyphenation is an option for Cell that specifies whether to allow hyphenation for words of text.

$Packages gives a list of the contexts corresponding to all packages which have been loaded in your current Mathematica session.