A Wireless Sensor Network (WSN) is composed of multiple sensors distributed over a certain range. The sensors send the acquired data via wireless to a common point. Thus, information about a specific area is combined and linked.
"Typically, the number of nodes in a WSN is an order of magnitude higher than in any other network, due to their compact size, cheap design, and required area of sensing coverage. Traditionally, the nodes are spread across a sensor field, and sink node(s) are designated that connect to a backhaul, possibly the Internet, that transport sensed data to external server(s) for storage and analysis. Often, the data are transported through multiple hops to reach the sink, so mesh networks share a lot of the same challenges as WSNs. For example, both must address bottleneck nodes through which most or all packets must travel between two network segments. In mesh networks, this is usually just a restriction on bandwidth. However, WSNs are almost always battery powered, so in addition to bandwidth, they must conserve energy to improve longevity of the network. This has been an active area of research for years and will continue to be so, in addition to an area of commercial innovation, as Internet of Things (IoT) device deployments scale up.
"Most application-specific WSNs are laid as pre-existing infrastructure such as in Supervisory Control and Data Acquisition (SCADA), IoT, and Smart Cities. WSNs typically are used for structural monitoring (residential, commercial, or civic) and environment and habitat monitoring."