Fountain pens are the grandparents of today's ballpoint and roller ball pens. They consist of a hollow shaft that you fill with ink, a tiny vein that allows the ink to flow to the point, or nib, and another tiny vein that allows air into the ink chamber to balance the internal pressure. Fountain pen nibs are split to control the flow of ink onto the paper. Most fountain pens have changeable writing tips. This allows you to clean or replace pen nibs, and also to change styles for different types of writing.
Hold the fountain pen with the writing tip pointing up and carefully wipe the nib clean with a soft cloth or disposable wipe.
Grasp the fountain pen nib at its base and gently wiggle it while you tug. If it does not come out, twist it counterclockwise. Some fountain pen nibs have screw threads and can't simply be lifted out without unscrewing them.
Seat the new nib carefully into the opening of the fountain pen and either gently press it into place, or screw it in clockwise if it has threads.
Clean your fountain pen regularly to avoid clogs.
Never carry a half-empty fountain pen onto an aeroplane, because the cabin pressure can cause the ink to leak or even spurt. Either fill the pen completely or empty it out before packing it.