Network Interface Card (NIC): Connects computers to the network cabling system. An example is an ethernet.
Modem: Converts digital signals to analog and analog signals to digital when dial-up services are needed. Examples include analogs and CSU/DSU.
RJ-11, RJ-45: Connects modems via household wiring to a POTS (telecommuncations) infrastructure, or a network card to a network.
TCP/IP: Lets dissimilar systems communicate via a communications protocol suite.
Web browser: Facilitates the display of various Web sites.
Email: Delivers electronic messages globally to Internet users via a common application.
Operating system: Controls how network system resources are managed and are needed on both the client and the server.
An IT system consists of one or more computer systems; multiple computer systems are connected together using some type of network interconnectivity. As a matter of necessity, network interfaces must conform to standard agreements, known as protocols, for messages to be understood by both computers during a message exchange between a pair of computers. The network itself can take on a variety of forms, provided that the interface requirements are met, and are determined by such characteristics as performance, convenience, and cost.
The work performed by an individual computer system within the IT system can be characterized by input, processing, and output.
This characterization is often represented by the Input-Process-Output (IPO)model shown below.
Storage is also represented within this model. Alternatively, storage can be interpreted as output to be saved for use as future input. Storage is also used to
hold the software programs that determine the processing operations to be performed. The ability to store programs and data on a temporary, short-term,
or long-term basis is fundamental to the system.
All IT systems can ultimately be characterized by the same basic IPO model at all levels, from a single computer to a complex aggregation of computers, although the complexity of large systems may obscure the model and
make it more difficult to determine the actual inputs, outputs, and processing