If you use a text‐based interface to the Wolfram Language, then the input you give must consist only of characters that you can type directly on your computer keyboard. But if you use a notebook interface then other kinds of input become possible.
There are palettes provided which operate like extensions of your keyboard, and which have buttons that you can click to enter particular forms. You can access standard palettes using the Palettes menu.
You can also give input by using special keys on your keyboard. Pressing one of these keys does not lead to an ordinary character being entered, but instead typically causes some action to occur or some structure to be created.
|EsceeEsc||the symbol for the exponential constant (equivalent to E)|
|EsciiEsc||the symbol for (equivalent to I)|
|EscdegEsc||the symbol (equivalent to Degree)|
|Ctrl+^ or Ctrl+6||go to the superscript for a power|
|Ctrl+/||go to the denominator for a fraction|
|Ctrl+@ or Ctrl+2||go into a square root|
|Ctrl+Space||return from a superscript, denominator or square root|
In a traditional computer language such as C, Fortran, Java, or Perl, the input you give must always consist of a string of ordinary characters that can be typed directly on a keyboard. But the Wolfram Language also allows you to give input that contains special characters, superscripts, built‐up fractions, and so on.
The language incorporates many features of traditional mathematical notation. But you should realize that the goal of the language is to provide a precise and consistent way to specify computations. And as a result, it does not follow all of the somewhat haphazard details of traditional mathematical notation.
Nevertheless, as discussed in "Forms of Input and Output", it is always possible to get the Wolfram Language to produce output that imitates every aspect of traditional mathematical notation. And it is also possible for the Wolfram Language to import text that uses such notation, and to some extent to translate it into its own more precise language.