The text library exposes a collection of interfaces (functions and operators) concerned with text operations.
The data type making the object of the text library functionality is the intrinsic string type.
See Intrinsic Types.
At least for the purpose of this library, data of the intrinsic string type is immutable (that is to say that it cannot be modified). And for that most of the text library exposed interfaces are string generators, i.e. the functions (and operators) made available by this library create new strings rather than modifying existing ones.
Most of the string generators of the text library create (the strings as) temporaries. Temporaries are bits of data not recorded with the expression evaluation or program execution logic and thus the application using this library must arrange for the eventual deallocation of resources (memory) reserved by the generated strings.