Estimate Cost is a process to get an approximation of real values needed to complete the work in a project. For Project Management this process is performed periodically as needed. Looking for one solution, align over PMBoK Six Edition, we try to keep the same input and output of this process.
We are using time, cost and resources (workers) to predict what the best configuration (for the features used) can bringing up the success of the projects.
The explanatory document can be read on LinkedIn.