So what is a bitmap font?
Every game developer has face it during the development: Display a text in the game to show damages or a conversation between two characters. For performance reason, standard fonts (understand TTF ) are not used directly. The preferred way is to use a bitmap font: it is a big image containing all characters used to display a text for a predefined size. The image (a png file) is linked with a text file with the extension fnt describing where each character is located in the image and give all necessary information to display the text. (base height, interline, …).