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[Mighty Midget]

The symbols just show what types of files they are. If you have "show file extention" enabled in folder options, you will learn quickly what the different symbols mean. For instance, the icons that look like blue windows usually mean they are executable files (extension EXE), that is a file you can run, in other words: A program.
The icon looking like a blue window with a cog wheel can be a batch file (extension BAT). A batch file is an executable file with a set of instruction, often used to automaticly run a set of exe files in a particular order.

However, in DOS (DOSBox you won't see these icons and all you have to think about is to look at the extensions when you type dir.