Difference between Verification and Validation with methods of verification process

Verification:-

1.        In general, Verification is defined as “Are we building PRODUCT RIGHT?” i.e., Verification is a process that makes it sure that the software product is developed in the right way. The software should confirm to its predefined specifications, as the product development goes through different stages, an analysis is done to ensure that all required specifications are met.
2.        During the Verification, the work product (the ready part of the Software being developed and various documentations) is reviewed/examined personally by one or more persons in order to find and point out the defects in it. This process helps in prevention of potential bugs, which may cause in failure of the project.
3.        Verification process describes whether the outputs are according to inputs or not.

Validation:-

1.        In general, Validation is defined as “Are we building RIGHT PRODUCT?” i.e., the product should satisfy all the functional requirements set by the user. Validation is done during or at the end of the development process in order to determine whether the product satisfies specified requirements. 
2.        Validation process describes whether the software is accepted by the user or not.
3.        Validation and Verification processes go hand in hand, but visibly Validation process starts after Verification process ends (after coding of the product ends). Each Verification activity (such as Requirement Specification Verification, Functional design Verification etc.) has its corresponding Validation activity (such as Functional Validation/Testing, Code Validation/Testing, System/Integration Validation etc...).

Verification	Validation
1. Verification is a static practice of verifying documents, design, code and program.	1. Validation is a dynamic mechanism of validating and testing the actual product.
2. It does not involve executing the code.	2. It always involves executing the code.
3. It is human based checking of documents and files.	3. It is computer based execution of program.
4. Verification uses methods like inspections, reviews, walkthroughs, and Desk-checking etc.	4. Validation uses methods like black box (functional)  testing, gray box testing, and white box (structural) testing etc.
5. Verification is to check whether the software conforms to specifications.	5. Validation is to check whether software meets the customer expectations and requirements.
6. It can catch errors that validation cannot catch. It is low level exercise.	6. It can catch errors that verification cannot catch. It is High Level Exercise.
7. Target is requirements specification, application and software architecture, high level, complete design, and database design etc.	7. Target is actual product-a unit, a module, a bent of integrated modules, and effective final product.
8. Verification is done by QA team to ensure that the software is as per the specifications in the SRS document.	8. Validation is carried out with the involvement of testing team.
9. It generally comes first-done before validation.	9. It generally follows after verification.

Methods of Verification

1. Walkthrough

2. Inspection

3. Review

Methods of Validation

1. Testing

2. End Users

What is Review?

Review is a process of inspection / walk through of software work products generated at different phases of Software Development Life Cycle or modified during maintenance, conversion and migration.

It is done over both executable and non-executable software work products to identify defects in creation / modification stages.

Stages of Review

Self Review:       Conducted by the Author

Peer Review:     Carried out by Peers

SQA Review:      Carried by SQA team

Types of Review:

Informal Reviews:

• No Formal Process.
• Results may be documented.
• Varies in usefulness depending on reviewers.
• Main Purpose: Inexpensive way to get some benefit.

Walkthrough:

• Walkthroughs are used to review small documents and products related to routine activities.
• Meeting led by the author
• May take the form of scenarios , dry runs peer participation
• Optional Preparation of review report including list of findings
• Main Purpose: Learning , gaining, understanding, finding defects

Inspection:

• Inspections are used to review large or critical documents / products having direct impact on functionality or external commitments where review by a single individual cannot uncover all the defects.
• It is usually led by a trained moderator (certainly not by the author).
• It uses defined roles during the process.
• It involves peers to examine the product.
• Rules and checklists are used during the preparation phase.
• A separate preparation is carried out during which the product is examined and the defects are found.
• The defects found are documented in a logging list or issue log.
• A formal follow-up is carried out by the moderator applying exit criteria.
• Optionally, a causal analysis step is introduced to address process improvement issues and learn from the defects found.
• Metrics are gathered and analyzed to optimize the process.

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