This feature probably accounts for LISP's success in competition with these languages, especially when large programs have to be written. One can even conjecture that LISP owes its survival specifically to the fact that its programs are lists, which everyone, including me, has regarded as a disadvantage. Whitespace is ignored. In general, case is ignored by automatically translating everything to upper case, except within strings or when specifying individual characters as data. This behavior can be changed by the user.
Characters can have names.
There are a few others as well, and more can be defined by the user. There are a few other single character dispatching characters, and more can be defined by the user. Everything else is either a number of a symbol. The reader is smart enough to recognize all the usual representations for integer, rational or floating point numbers. The base for rational numbers can be specified by the user.