Final answer:
A fitness tracker is considered an input device as its primary function is to collect data through sensors and provide that data to other systems for analysis and tracking.
Step-by-step explanation:
A fitness tracker is an example of a(n) input device. Fitness trackers are wearable devices that measure and record various types of data, such as the number of steps walked, heart rate, quality of sleep, steps climbed, and various other personal metrics. These devices typically contain sensors that detect physical or physiological changes and convert them into data, which is then processed by the device.
While fitness trackers do have the capability to display information, making them also an output device, their primary function is to collect data from the user's activities. Thus, when considering their main purpose, they are classified as input devices because they bring information into another system (like a smartphone or computer) for further analysis and tracking over time.
The data collected by health and fitness trackers can often be synced with mobile apps or computer software via Bluetooth or another connection method, which allows users to track their progress and health trends over time.