When you hold down a key instead of pressing and releasing it, the key repeats, like thissssssssss. You can change the speed at which keys repeat by using the Repeat Speed option. Press Right Arrow to make keys repeat faster; Left Arrow to make keys repeat slower.
You can use the Repeat Delay option to change the amount of time it takes from the time you press and hold down a key until it starts repeating.
Double clicking means pressing and releasing the mouse button twice in rapid succession. It's a shortcut you'll learn about when you use mouse-based applications. The application interprets your two clicks as a double-click only if the two clicks are done within a certain time interval. You can change the time interval by using the Double Click option.
In many applications, the cursor flashes to distinguish it from other characters on the screen. You can speed up or slow down the interval between flashes by using the Cursor Flash option.
Appendix A: The Control Panel Program