Each semester formally begins with you enrolling in subjects. The semester ends with exams, and before them students have the right to evaluate completed subjects, write what was good, what wasn't.
Evaluation process
At the end of December students start receiving emails asking to evaluate the completed semester. Simultaneously, the administration daily brainwashes teachers with requests to convince students by hook or by crook to participate in this.
Those who still aren't too lazy start filling out questionnaires. It will take about 10 minutes. In total, I received 5 emails, despite the fact that I gave grades long ago. Not all students apparently like this idea, especially during exams.
Questions, grading system
Students should go to the link http://hodnoceni.ff.cuni.cz/student/ and log in using standard login and password.
Then for each subject you'll need to go through a uniform list of questions - was the subject good, was it difficult, was the teacher good, etc.
As you can see, the questions are quite simple. Some don't need to be answered. For some you can leave comments. Usually, they're the most interesting.
For students who just enrolled (me, for example) as a bonus it was suggested to evaluate how the entrance exams went.
Anonymity
The main feature of the whole system is anonymity. Thus, you definitely won't get anything for bad grades. The only thing that can point to you is comments, but leaving them is completely optional.
Results
After all the running around, evaluation results are put on display. You can always find them here, for example, the latest - http://hodnoceni.ff.cuni.cz/hodnoceni-vyuky/35/?Rok=2014&Sem=Z&Loc=ustavy
Point of the endeavor
Actually, anonymous evaluations carry a lot of useful things.
First, you can really influence how this or that subject will proceed. So, for example, you can ask the teacher to give more practical knowledge, not theoretical, or give more precise instructions for getting credit. Teachers usually meet students halfway.
Second, evaluation ensures that the university has practically no "frankly bad" teachers. At RUDN, for example, I had a share of inadequate teachers with whom nothing could be done, and there were also good but undervalued ones. In general, such a transparent system wouldn't hurt any education system.
Third, evaluation results can be used in different ways. So, before enrollment, I carefully studied grades, comments, thus I enrolled already being confident that nothing would interfere with studies at certain departments. Jumping ahead - I wasn't wrong with the department, according to tradition already formed, here are some of the highest grades among the whole faculty.
Already after enrollment it's worth looking at results to decide whether to enroll in this or that subject or not - it often happens that a subject giving you 1-2 credits is disproportionately difficult, such subjects should be avoided.