V-MODEL

V stands for verification and validation

Verification:-

It is a process of checking "Are we developing right software or not"

Validation:-

It is a process of checking "Are we developed software or not"as per given requirement of customer 

V-model is suitable for big size projects development which have clear requirement 

BRS(Business requirement specification):-

This document contains business requirement of customer in non technical form.it is prepared by business analyst

SRS(Software requirement specification):-

This document contain software requirement specification based on business requirement of customer in terms of functional requirement specification and non functional specification in technical form.it is prepared by system analyst

HLD(High level design):-

this document contain overall structure of software from base module to end module 

LLD(Low level design):-

This document contain internal process of each and every module 

Coding: 

This is at the bottom of the V-Shape model. Module design is converted into code by developers.

Advantages of V-model:

• Simple and easy to use.
• Testing activities like planning, test designing happens well before coding. This saves a lot of time. Hence higher chance of success over the waterfall model.
• Proactive defect tracking – that is defects are found at early stage.
• Avoids the downward flow of the defects.
• Works well for small projects where requirements are easily understood.

Disadvantages of V-model:

• Very rigid and least flexible.
• Software is developed during the implementation phase, so no early prototypes of the software are produced.
• If any changes happen in midway, then the test documents along with requirement documents has to be updated

When to use the V-model:

• The V-shaped model should be used for small to medium sized projects where requirements are clearly defined and fixed.
• The V-Shaped model should be chosen when ample technical resources are available with needed technical expertise.