The print head is the most critical component of a printer. To answer what is a print head's function, it is used to deliver the ink to the page that you are printing.
It consists of tiny nozzles with holes that are less than a hair strand's width. This can get clogged easily with dried ink if not maintained properly. Your print head is a consumable that can wear out over time and eventually require replacing. To ensure your print head has a long life, it will require proper and regular maintenance such as doing cleaning cycles when needed.
Most print head quality problems are a direct result of improper care of the print head. Proper installation, ongoing attention, and maintenance are the keys to maximizing the life of a print head.