Dpi is a way of measuring how finely a printer (or a scanner, or a printed picture) lays down dots in one inch of space. A higher number means smaller, tighter dots, so edges look sharper and photos look less rough. Home printing is often around 300 dpi; a quick draft can be much lower. Though actually, dpi is not really 'how much ink' in the sense of a wetter, darker page. A 600 dpi print is not automatically using more ink like a thicker pen. It is packing more dots into the same space, which is about detail, not about soaking the paper. People also mix dpi with ppi (pixels per inch), the same kind of counting for screens rather than ink. In casual talk, someone may say dpi when they only mean 'is this sharp enough to print?'