G-Shock is a line of watches by Casio. Although the G-Shock watch was designed for its ability to withstand hard knocks during sporting activities, the brand also has fashion cred. To satisfy collectors, Casio collaborates with designers and pop-culture figures to produce new models each year. Despite the wide variety, G-Shock watches all contain stopwatches, countdown timers and backlights, so G-Shock watch instructions are often similar. For more details about a particular model, see the link under Resources.

Locate your four main watch buttons to follow these G-Shock watch instructions. The top left button is A, the top right button is B, the bottom left button is C and the bottom right button is D. The watch has five main modes: timekeeping, a display of times around the world, a stopwatch, a countdown timer and an alarm mode. To switch between modes, press button C repeatedly. Press B in any mode to turn on the backlight and illuminate the screen.

Put your watch in timekeeping mode and press A until the seconds flash. Then press C to move between several options that you can change using buttons D and B to move either up or down. The sequence of options will be as follows: seconds, city code, daylight savings time, hour, minutes, 12/24-hour format, year, month and day. Once each option appears, you can either skip it by pushing C to get to the next option, or you can push D to increase the number, B to decrease the number, or toggle (in the cases of daylight savings time and the 12/24-hour option). Press A to exit the setting screen.

You can measure a simple elapsed time with your stopwatch, or you can get more advanced by measuring split times and two finishes. The range of the stopwatch is limited to 59 minutes, 59.99 seconds, when it starts over at 00.00. It keeps running until you stop it, even if you move to a different mode. To perform any of these timed functions, first enter the stopwatch mode. To measure elapsed time, press D to start, D to stop, D to restart and A to clear. To measure split time, press D to start, A to split, A to release the split, D to stop and A to clear. To measure two finishes, press D to start, A to split (for example, for the finish time of a runner), D to stop (for example, when a second runner finishes), A to split release (to display the time of the second runner) and A to clear.

The timer can count down anywhere from 1 minute to 24 hours. To set your countdown time, enter countdown mode. Press A until the hours flash and C to move between hours and minutes. When a setting is flashing, press D to increase or B to decrease the number. Press A to exit. To use your timer, press D to start it. An alarm will sound for 10 seconds at the end, which you can turn off by pushing any button. Press D to pause and then resume a countdown session. To stop the countdown, press D and then A.