$DynamicEvaluation is a symbol whose value is True if it is evaluated as part of the evaluation of a Dynamic.
$ImagingDevices gives a list of available imaging devices.
$ReleaseNumber is an integer which gives the current Mathematica kernel release number, and increases in successive releases.
"Values for Symbols" discussed how you can use transformation rules of the form x->value to replace symbols by values. The notion of transformation rules in Mathematica is, ...
FourierSeries, FourierTrigSeries, and FourierCoefficient are part of the Mathematica kernel. FourierSinCoefficient and FourierCosCoefficient are now in the built-in ...
Join
(Built-in Mathematica Symbol) Join[list_1, list_2, ...] concatenates lists or other expressions that share the same head.Join[list_1, list_2, ..., n] joins the objects at level n in each of the list_i.
RuntimeOptions is an option for Compile that specifies runtime settings for the compiled function it creates.
TimeConstraint is an option for various algorithmic functions which specifies how long to spend trying a particular transformation or part of an algorithm.
ToeplitzMatrix[n] gives the n*n Toeplitz matrix with first row and first column being successive integers.ToeplitzMatrix[{c_1, c_2, ..., c_n}] gives the Toeplitz matrix whose ...
RowReduce[m] gives the row-reduced form of the matrix m.