This application note explains about low power modes available in Atmel® | SMART SAM3/SAM4 Microcontroller family. This application note also gives a walkthrough on information, techniques, and strategies, which can help in achieving low power with Atmel SMART ARM®-based MCUs. In low power targeted applications, many factors have to be considered to bring down the power consumption of an MCU. These includes specific low power configurations in the MCU, external components used and the hardware design. This application note helps the readers in understanding the internal settings and configurations of SAM3/SAM4 MCUs, which can give better low power performance. The SAM4L MCUs series has picoPower® technology for ultra-low power consumption, which supports multiple power configurations to allow the user to optimize its power consumption in different use cases. This application note also demonstrates low power measurement with Atmel Xplained Pro kits.