.NET - Object-Oriented Programming

What are structures?
Structure is a heterogeneous collection of elements referenced by the same name. A structure is declared using the struct keyword. The following is an example that creates a structure to store an employee's information:
struct emp
 fixed int empID[15];
 fixed char name[30];
 fixed char addr[50];
 fixed char dept[15];
 fixed char desig[15];
The preceding example defines a structure emp and the members of this structure specify the information of an employee.

When do you really need to create an abstract class?
We define abstract classes when we define a template that needs to be followed by all the derived classes.