onts are vector data that gets rasterized when displayed to the user. Computer displays are low-DPI devices for complex reasons, and such DPI (96) is not enough to display fonts without a myriad of trade-offs. Most notable are sub-pixel rendering, sub-pixel positioning, font hinting and anti-aliasing. You can read up more here and here if you want the full background.
Each operating system approaches font rendering differently. To get Windows-like rendering that I prefer, anti-aliasing, sub-pixel rendering, sub-pixel positioning and font hinting based on byte code embedded into fonts – basically, every step of the technological progress made in the last 30 years – need to be active.
