StartOfLine represents the start of a line in a string for purposes of matching in StringExpression.

When you enter a piece of input such as 2+2, Mathematica first recognizes the + as an operator and constructs the expression Plus[2,2], then uses the built-in rules for Plus ...

Whenever machine-precision numbers appear in a calculation, the whole calculation is typically done in machine precision. Mathematica will then give machine-precision numbers ...

Degree gives the number of radians in one degree. It has a numerical value of \[Pi]/180.

Dynamic and Manipulate have holding attributes that are vital in making them work properly. However, those holding attributes can interfere with other structural operations ...

StringDrop["string", n] gives " string" with its first n characters dropped. StringDrop["string", -n] gives " string" with its last n characters dropped. StringDrop["string", ...

"s_1" <> "s_2" <> ..., StringJoin["s_1", "s_2", ...], or StringJoin[{"s_1", "s_2", ...}] yields a string consisting of a concatenation of the s_i.

Power series are represented in Mathematica as SeriesData objects. The power series is printed out as a sum of terms, ending with O[x] raised to a power. Internally, however, ...

FullForm[expr] prints as the full form of expr, with no special syntax.

TraditionalForm[expr] prints as an approximation to the traditional mathematical notation for expr.