Squeezing your Filesize (KB) - Tutorial

There are lots of cases where you want to squeeze a picture's filesize. Sometimes a small picture can be 250+ KB while a bigger picture can be only 10KB. This is because of the different filetypes. Today I'm going to teach you, how to choose the optimal filetype for your picture. Although this tutorial uses GIMP (all the instructions about plugins and menus are for GIMP), this should help users of other programs that have basic understanding of their program.