Mathematica allows arbitrary hierachical namespaces. However, several standard "contexts" are conventionally used for predefined purposes.
Mathematica has flexible capabilities for per-machine or network license management.
BinaryFormat is an option for OpenRead and related functions that specifies that a stream should be opened in binary format, so that no textual interpretation of newlines or ...
Catalan
(Built-in Mathematica Symbol) Catalan is Catalan's constant, with numerical value \[TildeEqual] 0.915966.
Expression is a symbol that represents an ordinary Mathematica expression in Read and related functions.
PoissonDistribution[\[Mu]] represents a Poisson distribution with mean \[Mu].
PolynomialRemainder[p, q, x] gives the remainder from dividing p by q, treated as polynomials in x.
FillingStyle is an option for ListPlot, Plot, Plot3D, and related functions that specifies the default style of filling to be used.
NakagamiDistribution[\[Mu], \[Omega]] represents a Nakagami distribution with shape parameter \[Mu] and spread parameter \[Omega].
Optimum
(Combinatorica Package Symbol) Optimum is a value that the option Algorithm can take on when used in functions VertexColoring and VertexCover.