C Basic Syntax

The C language syntax specify rules for sequence of characters to be written in C language. The rule specify how the character sequence will be grouped together. A smallest individual unit in C program is known as C Token. Tokens are either keywords, identifiers, constants, variables or any symbol which has some meaning in C language.

Now for example lets take a look at below C example code :
#include <stdio.h>

int main() {

  printf("Hello world.!!\n");
  return 0;

If we take a line of statement,
printf("Hello world.!!\n");
The tokens at the above lines are printf, (, "Hello world.!!\n", ) and ;. So we can say that basically C tokens are the building blocks of a C program.

Semicolons : 

In a C program, the semicolon is a statement terminator. That is, each individual statement must be ended with a semicolon. It indicates the end of one logical entity. Absence of semicolon at the end of any statement, will mislead the compiler to think that this statement is not yet finished and it will add the next consecutive statement after it, which may lead to compilation(syntax) error.
printf("Hello world.!!\n");

return 0;

Whitespace in C :

A line containing only whitespace is known as a blank line, and a C compiler totally ignores it. Whitespace is the term used in C to describe blanks, tabs, newline characters and comments. Whitespace separates one part of a statement from another and enables the compiler to identify where one element in a statement, such as int, ends and the next element begins. For example :
return 0;
Some of the basic syntax rule is as follows :

1. C is a case sensitive language so all C instructions must be written in lower case letter.
2. All C statement must end with a semicolon.
3. Whitespace is used in C to describe blanks and tabs.
4. Whitespace is required between keywords and identifiers.