Most of the defects in software products have around conditions and boundaries. By boundaries, we mean “limits” of values of the various variables. This is one of the software testing technique in which the test cases are designed to include values at the boundary.

If the input data is used within the boundary value limits, then it is said to be Positive Testing.

If the input data is picked outside the boundary value limits, then it is said to be Negative Testing. Boundary value analysis is another black box test design technique and it is used to find the errors at boundaries of input domain rather than finding those errors in the center of input. Each boundary has a valid boundary value and an invalid boundary value.

Test cases are designed based on the both valid and invalid boundary values. Typically, we choose one test case from each boundary. Boundary value analysis help identify the test cases that are most likely to uncover defects.

Some examples of Boundary value analysis concept are: If the can accept he numbers between 1 to 100.Then One test case for exact boundary values of input domains each means 1 and 100. One test case for just below boundary value of input domains each means 0 and 99. One test case for just above boundary values of input domains each means 2 and 101. Under this technique, boundary values 0,1, 2, 99,100,101can be tested. Out of which 1,2,99,100 are valid values and 0,101 are invalid values.