How do you define critical success factors for project ?

Alok, there is also a difference between objectives and critical success factors.

wikipedia: "Critical success factors are those few things that must go well to ensure success for a manager or an organization and, therefore, they represent those managerial or enterprise areas that must be given special and continual attention to bring about high performance. CSFs include issues vital to an organization's current operating activities and to its future success."

CSFs for a project are the prerequisites to make achievement of the particular objectives (scope, time, cost etc) more probable. They are different per project situation, but could be just modeled after the 10 PMBoK knowledge areas. As to many surveys why projects go wrong, I would suggest that key CSFs are attacking these key reasons for project failures:
- stakeholder analysis and engagement
- communication
- scope management

Alok, as Sergio also pointed out, there is a difference between the project and it's result, the product.

A project might be successful delivering what it was asked for but the product then might be useless (Example: building a bridge but not being able to build the streets leading to and from it). I assume it was not in scope of the project to build the bridge to ensure the streets are build too. Happens all the time.
A product might be successful, but the project might be considered failed. (Example: Sydney opera house, now considered a landmark building and providing pride and reputation to Sydney, though the architect and project managers were fired, similar with Hamburg Philharmony). Happens all the time, in particular with public projects.

The point is: a project has to make project stakeholders happy, the product has to make the product stakeholders happy. These might be different groups at different times.

If you want both projects and products to be successful, project management is not enough, you need program management including benefits management. Sergio would add business analysts.

For more on the difference between projects and programs read on here:
https://www.slideshare.net/walenta/prtesen...w-december-2014

Is a project successful if it is delivered on time and budget but the product of the project is never fully utilised? I think not. Projects are not done to deliver "Shelf-ware". The only reason we do projects is for the added benefit they provide. Saying a project is a success or failure based on the time/cost/quality dimensions is a flawed argument. So what if it takes some time after the project has completed to say whether it is a success or not? Really valuable lessons learnt can be gathered in the light of the ultimate outcome of the project - success or failure! So measure project success on the value of the outcome not how much it cost or how long it took to deliver.

All-
This is the Construction topic section?
In my Industry, we tend to avoid the complicated and esoteric analysis provided above. Professionally, I could not Instruct my Execution Team based upon the responses above, nor would they care about the PMBOK concepts.
To achieve a "successful" Project (handover the proposed Deliverable) My Team needs to meet the Schedule, deliver the SOW, hit their proposed Quality marks, and make the Client Happy.
It is a very simple game plan for the Execution Team. Achieving it takes a huge effort from all the support groups (Procurement, Project Controls, Doc Controls, Design, HR, Safety Team, Quality team) to support them.
From the Trenches!
M

Alok,

Success factor can be different for each stakeholder.

For the executing company, it could be profit generated.
For the client, timely delivery, meeting expectation, quality

Someway I see it has benefit realization, what were the expected benefits? that will varies.