There are all sorts of opinions on this and, for the most part, it just comes down to preference. That said, there are some very valid reasons for choosing one or the other, particularly in certain circumstances.
I’ll get into details below, but here’s what I generally recommend:
- Black ink for filling out official records.
- Blue for business signatures and most others.
- Black for memos and work correspondence.
- Blue (or red) for notes and most learning purposes.
- Blue for credit card applications.
- Blue (or another color) for creative purposes.