BVA & ECP

Equivalence Class Partition (ECP): Means dividing the input 
Domain into groups and name these groups as Valid and 
Invalid. By Using these groups we can derive the Test Cases.

Boundary Value Analysis (BVA): Means finding the boudaries 
for given particular value. By Using these boundaries there 
is maximum possibilities of finding Bugs/Defects in an 
Application.

Example: In an Application User ID takes 5 to 10 Alphabets. 
It is the Customer required.

Solution:
User ID: 5-10 Alphabets

ECP:
Valid          Invalid
A-Z            0-9    
a-z            Special Charecters
               Blank Field

BVA:
Min       = 5        Pass
Min-1     = 3        Fail
Min+1     = 6        Pass
Max       = 10       Pass
Max-1     = 9        Pass
Max+1     = 11       Fail