What DPI should I buy?

Hello there, I'm curious about the DPI, or dots per inch, that I should be looking for when I'm in the market for a new monitor or display device. Could you please shed some light on what DPI is, and how it affects the overall quality of the image or visual output? Additionally, are there any specific DPI ranges that are considered optimal for certain types of tasks, such as gaming, graphic design, or watching movies? Your insights would be greatly appreciated!