Pens are fascinating. While they may look very straight forward, there are composed of a multiple of parts. All which have to fit together perfectly, each with a function to perform.
There are two things about owning a fountain pen that make it very different from the disposable ball point pen.
Pens in some form have been around for a long time. Whether quills, or sticks with iron nibs for dipping, pens have been an important part of communication.
In terms of actual pens, at first they were made with a steel nib that was dipped in ink. The pen was used at one's desk. Or, ink, bottles, blotting powder or paper were transported with the person to set up a writing desk - possible, but not really that mobile.
The next major innovation was to have the pen body hold ink. These pens generally had problems. In 1870 Lewis Edson Waterman invented the now famous system to control the flow of ink from the ink chamber to the nib. He developed a three-channel feed that would allow air to travel up into the ink chamber while ink flowed out.
Pens went through some innovations, an eyedropper was used ti get the ink into the ink chamber. Then the pens progressed so that the ink would be drawn up into the pen body through the nib.
Since that time there have been innovations in terms of the materials used to make the pens, however, the basic workings of the pen remain fairly consistent.
The links below provide further information about fountain pens.