Fonts - Bitmap Fonts
Bitmap fonts are faster to render, and often smaller to store (but that does depend on the size of the character and whether the bitmaps are being compressed).
If a full set of bitmaps are stored in an array and indexed according to the ASCII table then it is trivial to locate the bitmap corresponding to each letter in the string stored in your program.
By looping through any string, displaying the corresponding bitmap, and moving the position to the right as you go, a simple printing routine can be implemented.
Notes:
By switching to bitmap fonts we save CPU cycles and storage space - except maybe in the rare case where the bitmaps are huge, and would actually take up more space than the general form stored in a scaled font.
Each bitmap can be accessed with an array where the index of the array corresponds to an ASCII character, or maybe a different mapping if you are implementing Japanese or Chinese characters - but more on international character sets later.
Displaying a string is a simple case of taking the string that needs to be displayed and displaying the bitmap for each letter in the string. As each bitmap is displayed, the current position has to be moved to the right by the width of one character.