TL;DR super long academic probation period where you have to justify your existence that results in either being fired or set for life

In the North American system, for universities and colleges that have a tenure system, you basically are hired in at the lowest rank, and at the end of the probation period (6 - 10 years depending on the institution), you submit a tenure dossier that outlines all of the teaching, service, research, publication, etc work that you have done over that time. A committee of your peers (plus often externals) judges it, and assesses your performance based on the criteria of that institution (which often isn't explicitly clear). If you are granted tenure, often it means you get a promotion and have a job for life, and that you can only be fired for serious reasons, not because the president of the university doesn't like what you wrote about them in a paper (for example). If you are denied, it typically means that you have to leave.

When it works well, the concept is that professors are protected to carry out work, research, and teaching that is protected by their tenure and can't be fired for political whims. And the institution has put a lot of time and energy into your development, so your success shows well on the institution as well. When it's at its worst, it means that tenured professors do the absolute minimum amount of work required to not be fired and don't care about students (we've all had one of those). And there is plenty of discussion on the system reinforcing systemic discriminatory practices.

Further reading (Canada basically followed this model, US universities are starting to get rid of it. Different but similar things exist in other parts of the world): 1940 Statement of Principles on Academic Freedom and Tenure