Speed hacking is a program that increases the rate at which a program will run, more often than not used in games. This only affects your own client unless you are the host. In most multiplayer games that means instead of the entire game engine speeding up including other clients, only certain parameters are of the speed hacking client. The most common parameter affected is movement. If a player moves at a certain speed, they will "teleport" due to the server unable to constantly keep track of their enhanced movement. Desync and modem tapping are not speed hacking. Desync is constant and happens to everyone. It is your ability to to connect to the server from your client and vice verse. In layman's terms, it is lag. Your ping determines how much that is. If your ping is 500 MS, you have to wait a 1/2 second for the server to receive your client's new information or vice verse. Perfect ping is 0 MS. Great ping is 50 or less. Good ping is 100 or less. Average ping is 200 or less. Bad ping is beyond that. If the game doesn't display that information, you can always use command prompt to check. Modem tapping is an intentional disconnect of the client and the server. This allows you to do things in your client, then reconnect to apply those things such as moving to a new location (which will cause you to teleport), but depending on the game, what you can do overall varies. This is potentially exploitable, but difficult to prove since it is very similar to just lagging out. The easiest and most common way to speed hack is cheat engine. It takes however long to download and install it, from then on just 10 seconds total to; open it up, select the program you want to alter, enter what multiplier for speed hack, then click the check box to apply it. In regards to the "colorful boxes on survivors and zombies to show where they are", that's an aim bot mod.