This article presents a study of the state of the art of sensor networks wireless systems, which continue to develop and present a wide variety of Applications. These networks constitute a current and emerging field of study where combines the development of computers, wireless communications and devices mobile phones and integration with other disciplines such as agriculture, biology, medicine, etc. I know presents the main concept, components, topologies, standards, applications, problems and challenges, then delves into security solutions and concludes with basic simulation tools.