In a fountain.

(Having to change into swim trunks to take notes in a meeting is a bit awkward.)
They're very much like a ballpoint in terms of use when writing, but because most of mine use a refillable internal reservoir, I can choose from a number of inks - I have something like a dozen different bottles in various colors. Basically there's a very fine channel to allow the ink to flow to the tip of the pen, and the size of that channel and the viscosity of the ink prevent it from running out unless the paper is wicking the ink from the tip.