Expressions in Mathematica can be represented as strings in a variety of ways, for display, export, or processing. Mathematica provides powerful functions for formatting expressions as strings, and for parsing strings to determine the expressions they represent.
ToString — convert any expression to a string
ToExpression — convert a string to an expression
ImportString — import many formats of strings to give expressions
ExportString — export expressions to give many formats of strings
IntegerString — convert an integer to a string
SpokenString — convert to a spoken representation of an expression