The Internet Computer blockchain runs on a network of special computing devices called "node machines" that are installed in independent data centers by independent "node providers". These node machines connect to each other using the Internet Computer Protocol (ICP), which is where the token gets its name.
The network has a governance system called the Network Nervous System (NNS) that can "slash" or eject node machines that fail to produce enough blocks and keep up with the network. This is why the node machines need to be built to a specific standard.
Internally, the Internet Computer network is composed of "subnet blockchains", where each new subnet adds additional capacity to the network to host more smart contracts, computation and data. However, these subnets are invisible to the hosted smart contracts and users.