Wireless grids are wireless computer networks consisting of different types of electronic devices with the ability to share their resources with any other device in the network in an ad hoc manner. A definition of the wireless grid can be given as: "Ad hoc, distributed resource-sharing networks between heterogeneous wireless devices" The following key characteristics further clarify this concept: No centralized control Small, low powered devices Heterogeneous applications and interfaces New types of resources like cameras, GPS trackers and sensors Dynamic and unstable users / resources The technologies that make up the wireless grid can be divided into two main categories; ad hoc networking and grid computing. (Wireless) Ad hoc networking In traditional networks, both wired and wireless, the connected devices, or nodes, depend on dedicated devices (edge devices) such as routers and/or servers for facilitating the throughput of information from one node to the other. These 'routing nodes' have the ability to determine where information is coming from and where it is supposed to go. They give out names and addresses (IP addresses) to each connected node and regulate the traffic between them. In wireless grids, such dedicated routing devices are not (always) available and the bandwidth that is permanently available to traditional networks has to be either 'borrowed' from an already existing network or publicly accessible bandwidth (open spectrum) has to be used. A group addressing this problem is MANET (Mobile Ad Hoc Network). Resource sharing One of the intended aspects of wireless grids is that it will facilitate the sharing of a wide variety of resources. These will include both technical as information resources. The former being bandwidth, QoS, and web services, but also computational power and data storage capacity. Information resources can include virtually any kind of data from databases and membership lists to pictures and directories. Ad hoc resource sharing between mobile devices in the wireless grid require for the devices to agree on sharing/communication protocols without the existence of dedicated servers. Coordination Systems Coordination Systems are the actual mechanisms that enable the sharing of resources between different devices. For different resources, devices use different coordination systems. Examples of such mechanisms are: SMB or NFS for sharing disk space and the distributed.net client for sharing processor cycles. Trust Establishment Before users are willing to share any resource, they demand a certain amount of trust between them and the users and/or systems they share resources with.