To develop a project through a detailed planning, there are basically two techniques: Critical Path Method and Program Evaluation Review techinique.

The CPM was founded in 1957 by the work of Walker and Kelly to improve the planning for the management of large construction projects at the organization Du Pont.

Instead PERT has its origins in the military to a certain number of researchers were asked to develop and implement a management system for the realization of a ballistic missile named "Polaris"

The main objective that was meant to be achieved, was to have the delivery of the finished product, the missile to a date certain and fixed.

Both PERT and CPM that are represented graphically by means of oriented features, which differs from the CPM PERT dealing with uncertainty in the project; Critical Path Method, adheres to the deterministic criteria and the PERT, Project Evolution Review Technique, is a mix between deterministic and stochastic.  

The PERT is convenient in the case of projects where the duration can be random while the CPM is more logical in situations where there is a need for more accurate and detailed definition of resources and time.

The main activities to be undertaken at the end of a correct application of methods of Perot CPM are as follows:

Definition of project activities that are going to take.

Temporality of the activities that are going to put in place technical specifications, contractual commitments.

Life cycle of the project.

Regardless of whether you are using the PERT or CPM will be used to break down the various stages of the project through the use of a Work Breakdown Structure (WBS), in this way, the project will have different levels of importance in being able to give a determined time and resources optimizing costs to be allocated to the management of the project.