Structures are a way of storing many different values in variables of potentially different types under the same name. This makes it a more modular program, which is easier to modify because its design makes things more compact. Structs are generally useful whenever a lot of data needs to be grouped together--for instance, they can be used to hold records from a database or to store information about contacts in an address book. In the contacts example, a struct could be used that would hold all of the information about a single contact--name, address, phone number, and so forth.

Syntax:
struct Tag {
  Members
};

Where Tag is the name of the entire type of structure and Members are the variables within the struct. To actually create a single structure the syntax is
 
struct Tag name_of_single_structure;
To access a variable of the structure it goes
 
name_of_single_structure.name_of_variable;

Example:
struct example {
  int x;
};
struct example an_example;
an_example.x = 33; 
Here is an example program:
 
struct database {
  int id_number;
  int age;
  float salary;
};

int main()
{
  database employee;
  employee.age = 22;
  employee.id_number = 1;
  employee.salary = 12000.21;
}