A data logger is an electronic device that records data. It usually comes with a sensor device which acquires the data. A temperature data logger will have a thermometer attached to it. The thermometer can be replaced by another sensor such as a sound meter to acquire and record a different set of data. This, of course, depends on the actual capability of the data logger.
The most common type of data loggers are stand alone devices that are multi-functional. The logger can interpret numerous types of electrical signals from different types of sensor devices and then have the ability to store the data in an internal memory. This information can then be transferred to a computer for further processing and archiving.
Data loggers come in several different shapes and sizes. They also vary in price which depends on device capabilities. Single channel loggers are generally cheaper than devices that can handle a multitude of inputs.
Data loggers are used for a multitude of reasons. Many major corporations use them for various functions. An example is with the trucking industry, in which data loggers are required to keep a record of the interior temperature when transporting food products. The logger can read and record various changes in temperature and warn against conditions that can spoil the food products.