One of the important skills that a programmer should possess is the ability to estimate task completion times. Estimating work durations plays a key role in project planning, as well as ensuring the realism of goals and commitments to managers, colleagues, and users. However, there are often misunderstandings regarding the concepts of estimation and commitment, and their differences are not always clear. I have experienced both sides of this issue and know firsthand how harmful it can be to a project. Therefore, I decided to write this article to help programmers and managers understand this issue.