BVA : If an input is bounded on 20 and 30 , the testcase 
should included the values 20 , 30 and Just above and below 
of 20,30 respectively.
ECP : if an input specified member of sets , then one valid 
and one invalid values included

Equivalence partitioning:- It is an black box testing 
technique and it can be defined as "Dividing the input 
domain of data into the class of interavels and from which 
we can prepare test cases.

Boundary value analysis:- It is also an black box technique 
majorly stress on boundary conditions.As the most of the 
bugs reside at boundaries.

BVA: Instead of we entering every possible input domain we
check the input domains with boundaries only.

Eg:empID takes 4-16 alphabets.

value - status.

min->4   pass
min-1->3 fail
min+1->5  pass
max->16   pass
max-1->15 pass
max+1->17 fail.

ECP:
with this we enter valid values enter as input domains.

Eg:
empID should accept 4-16 alphabets.

valid  - invalid

a-z       0-9
A-Z       spaces, special characters.

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