My answer to this Quora question 12 years ago [edited] is a remark on professionalism :

Letter grades and marks on transcripts can mean many things and depends entirely on who reviews your transcript. A 'W' can simply tell a practically-minded person "here's a person who attempted to accomplish something and decided it was inappropriate to continue pursuing it due to other responsibilities or interests." This is a very professional decision for a person to make. On the other end of the spectrum are those who see a 'W' and think the person is a quitter and doesn't finish what they set out to do. I don't think these people are practically-minded. (Would you want to work for them?)

The best one can do in this situation is to excel in other things such that a 'W' is but a mere flyspeck on their record and continue to make professional decisions going forward.

In my graduate work, a friend of mine and I had taken an electrical engineering course in design (VHDL) that was outside our area of expertise (we were primarily device fabrication and device physics students). Giving it the old "college try" for a few weeks, we found the professor to be quite bad at his job, and since we were having much more difficulty with the course than we ever imagined, we dropped it and took our 'W's. At the end of the semester more than half of the students (who were design engineering students and would have normally done wonderfully in the course compared to us) received 'C's. Two 'C's in most graduate engineering and science programs equates to dismissal. So, taking a 'W' was a very professional decision to make. In our case, we thought we were in over our heads, but realized that the professor was simply not very good and frequently misled students in their coursework.

A student who takes a 'W' does so for any of a countless number of reasons. Therefore, anyone who assumes that a 'W' represents failure, or is the mark of a quitter, should not be taken seriously.