Computer networks allow computers and devices to be interconnected so they can share resources and communicate. A computer network can connect devices either wired or wirelessly. Networks can be classified based on their geographical span, inter-connectivity, administration, and architecture. They range from small networks spanning a table to global networks spanning the world. Networks can have different topologies like mesh, bus, star, or hybrid configurations. Networks can be private, belonging to a single organization, or public. Common network applications include resource sharing, email, web browsing, and video conferencing. Networks transmit data over communication media like cables or wireless signals.