At my university, most lecturers and professors use slides in teaching. This is true for most engineering, mathematics and science courses. I am more comfortable with doing the board work and then sharing my hand-written lecture notes with the students. From my personal experience, I feel that the latter is a better way of teaching.
So, what are the advantages of using slides? Why do you use slides?
Secondly, does the answer to the above question change if you were teaching graduate students?