For most students this will be the longest, most difficult and most important assignment completed at university, requiring months of preparation and hard work (the library might become a second home).
If a student wished to advance further in academia he could pursue a dissertation. He would read widely in a particular area and write up his findings, discussing the various authorities and their opinions.
The point was to demonstrate that he was well versed in the literature of the field.
Non-empirical dissertations are based on existing data and arguments in the work of others.
This is likely to mean spending a lot of time with your head in a book!
A dissertation is part of a broader post-graduate research project.
However, the thesis has evolved since original research nowadays requires plenty of background research.
This may mean putting into practice professional and ethical guidelines when collecting data from members of the public.
Empirical dissertations in natural and life science subjects may involve or be entirely centered on laboratory work.
I attended a thesis defense recently in which the student was not well prepared.
The visuals were poor and disorganized and the student did not handle questions well.