The major purpose of this article is to know about data loggers. Data loggers usually have built-in clocks whose available drift can be a vital thought when deciding what device to decide. The loggers come in numerous dissimilar forms from essential single-channel input to problematical multi-channel devices. Usually, the most primary the gadget the less programming elasticity. The more multifaceted devices allow the user to carry out cross-channel computations. Also alarms produced for predetermined conditions.