Human: Can you tell me about the different kinds of pens? Assistant: 
There are a variety of types of pens available on the market, each with its own advantages and disadvantages. Ballpoint pens are typically cheaper than other types of pens, but they can be harder to write with due to their design. Fountain pens offer a smoother writing experience as the ink is stored in an internal reservoir, but they tend to be more expensive. Gel pens provide a thicker line and better color saturation than ballpoints or fountain pens, but they also cost more. Mechanical pencils have a graphite core that can be sharpened, but they require regular maintenance and can be prone to breaking.