Clocks have a variety of uses, from acting as timers, to creating blinking devices. Clocks are referred to by their speed, generally in the format X-clock, with X being the number of ticks that the clock stays on for before going low. The fastest clocks that can be made without the torches burning out is a 4-clock. There are 2 main ways to ways to create clocks.
String of NOT GatesEdit
A clock can be created by stringing together an odd number of NOT gates. The pulse width of the clock is dictated by the number of NOT gates in the clock. This method can only produce odd number clocks because an odd number of NOT gates is needed.
String of RepeatersEdit
A clock can also be made by making a line of repeaters, as shown in the image. This method is much more compact, and can be expanded infinitely. The pulse width of the clock is the sum of the repeater's delays. This method can create even number clocks. However, since this method still involves a redstone torch, it will burn out with anything less than a 4-clock.