"Have you ever needed a short Ethernet cable, but all the ones in your closet are six feet long? You could just wrap up the excess, but for a cleaner look, you can shorten the cable yourself. With the right materials, you can even make your own custom-length network cables.
By crimping your own Ethernet cables, you can make them in any length you want. Pre-made Ethernet cables only come in specific lengths, and you may need a size that isn't available. Again, you can always go longer than you need to, but it's mostly a waste."
Whenever you install something in Mac OS X then it gets installed from package files. Along with installing something from package files, a "Bill of Materials" file is stored in the package receipt file. These ".bom" files contain a list of the files installed by that package as well as the proper permissions for each file. But, in future, these permissions can get changed resulting in freezing or crashing of your Mac.