A host, more fully known as a network host, refers to a computer device which helps communicate with other hosts on a network. It includes the clients and servers which send or receive data, services, or applications. The idea of server and client can be interchangeable because a host can function either as a client and as a server, or as both at the same time.
In the field of mainframe computer environments, a ‘host’ represents a mainframe computer that provides host services to certain workstations. In this context, a ‘host’ is also known as a large server to the Internet audience.
In more general terms, the ‘host’ term is usually attached to a powerful device or program that delivers services to some smaller and less capable device(s) or program(s).
Host vs Server
The terms host and server are often used interchangeably, but they are two different things. All servers are hosts, but not all hosts are servers. To avoid confusion, servers are often defined as a specific type of host, such as a web host or mail host. For instance, a mail host and mail server may refer to the same thing.
While a server refers to a specific machine, a host may also refer to an organization that provides a service over the Internet. For example, a web host (or web hosting company) maintains multiple web servers and provides web hosting services for clients. A file host may provide online storage using multiple file servers. In other words, a hosting company hosts multiple servers that serve data to clients.