A data logger is a device used to record and store the output of one or more sensors. In some cases, the data logger interprets the electrical signal from the sensor and converts it to units. In cases where a smart sensor provides digital output, the data logger simply records the data. Early data loggers were strip chart recorders that recorded measurement data onto paper. Over time, data loggers evolved to store data digitally on various types of media. Today, data is typically stored on modern flash memory and often transmitted via a variety of telemetry methods.
Similar terms for "data logger" include "datalogger," "logger," "data recorder," "data acquisition system," and "RTU" (remote terminal unit). Which term is used often varies by industry or discipline.