Answer:
The net present value (NPV) is the most important and useful method of capital budgeting analysis. It is basically calculated by determining the present value of all the future cash flows generated by a project and then subtract the original investment cost. If the answer is positive (positive NPV) then the project should be profitable and the company should go ahead with it. The limitation of NPV results from the discount rate used to calculate the present value, since it is extremely important to use the proper discount rate and not one that is too low or too high.
The second most useful tool is the internal rate of return (IRR) which is very related to the NPV. The IRR shows us basically at what discount rate the NPV would equal 0. Generally if the IRR is higher than the discount rate the NPV should be positive.
The payback period shows us how much time it takes a project to recover the original amount of money invested in it. The payback period is only useful for some industries where early obsolescence might be a problem. E.g. technological firms only approve projects with very short payback periods because their products might be obsolete in just one or two years.