Precision stopwatches let you time multiple people or events with extreme accuracy. They are ideal for a number of fast-paced activities: sports, training, and racing are more accurate with precision stopwatches, which generally time to the hundredth of a second. Some high-end models have a number of other helpful functions and operate as calculators, alarms, or pedometers.
The advantage of digital timers over mechanical stopwatches, which time to only one-fifth a second, is more than one just of degree. Since precision stopwatches are in the digital format, there are simple functions that it can handle with ease that mechanical ones can't–such as a countdown timer. What you first need to figure out is what kind of functions you need from your stopwatch.
Some Uses for Precision Stopwatches
If high precision is of the utmost concern, or if you are timing multiple events, you will probably require a more advanced stopwatch that has a higher degree of accuracy than mechanical models. A ref at a swim meet, for instance, needs as much data as possible–digital stopwatches can handle multiple timings with ease. A lab technician doing important experiments needs the most accurate timing information available to make their research as precise as possible.
Less precise stopwatches are found at school, at home and in industry for a myriad of reasons. Sometimes the accuracy of one-fifth of a second is close enough for some–while playing games or cooking, for example–and the lower-tech models are sufficient. If all you are doing is timing single events (like a cake in the oven) a high-end digital model might be overkill.