Equalance nothing but select the valid and valid clases
example as per client requirement the edit box access onaly 
3-5 capital alphabets then we divided in ecp like vaid 
values only A-Z invalid values are a-z and special 
characters like ^,8<%

Equivalence partition is a group of test cases that tests 
the same thing or produce the same bug (or not). we usually 
use this test design technique to reduce test cases (and 
test time) and to assure best coverage.

Belal Raslan

Equivalence partitioning is a black-box testing method
	- divide the input domain of a program into classes 
of data
	- derive test cases based on these partitions.

Test case design for equivalence partitioning is based on 
an evaluation of equivalence classes for an input domain.

An equivalence class represents a set of valid or invalid 
states for input condition. 

An input condition is:
	- a specific numeric value, a range of values
	- a set of related values, or a Boolean condition

Ensure all the representative values have been considered
Example:
For login Id give all types of Inputs,
Small,Caps,Mixed("JohnDoe:,"johndoe",John123")