Speed is the number we read from the speedometer on our car: how fast we are going in miles per hour or in kilometers per hour. The larger the number, the faster one is moving. This number, while useful for cars, trains, planes, and boats, is not typically used by runners.
Track and field athletes speak in terms of their times, especially in shorter sprints such as 100 meters and 200 meters. Athletes have a "100 meter" time, such as 13.74 seconds to run 100 meters. For events longer than one 400 meter lap of the track athletes usually speak of their lap times: how long to run a single 400 meter lap.
Road runners focus on pace: the time in minutes and second to cover a single kilometer. Pace is the mathematical inverse of speed, although with a unit shift from hours to minutes. Road runners tend to focus on attaining a steady pace, although this pace will vary with terrain.
Road runners will say sentences like, "I ran a six-thirty kilometer on my run last night." That would mean that they averaged six minutes thirty seconds per kilometer. Runners from the United States tend to quote pace in minutes per mile.
The smaller the pace the faster one is moving (less time in minutes to cover one kilometer).
The pace at which you can sustain a jog over distance is baseline measure of one's personal physical fitness. Comparing your pace to others is not particularly useful, but knowing your own pace over the years is useful. Improvements in your sustainable pace are signs of improved personal fitness, decreases in your sustainable jogging pace are signs of a loss of fitness.
The Timex unit uses Global Positioning System (GPS) satellites to determine your pace and the distance you have traveled.
On the roads, Lee Ling tends to plod along at a six minute thirty second pace.