Syntax and Semantics
Every computer language has code that is made up of syntax and semantics. The syntax of a programming language is the basic skeleton your program has to follow so that the Emacs Lisp interpreter knows what's what in your program; so it can tell what's a function, a variable, etc. The semantics of a program are the more "random" stuff, like the different commands you have available and what variables you're allowed to look at at any point in the program. The first thing that is special about Lisp is that it has the simplest syntax of any major programming language.
Basically, the Lisp syntax dictates that any text you give the Emacs Lisp interpreter has to be arranged into lists, which can be nested into lists of lists as deeply as needed. Parentheses are used to mark the beginning and end of each list:
A list in Lisp
<< begin < previous - next > end >>