Here's one definition of a system:
A set of related component parts brought together to form an inter-connected unified whole to perform some function.Hmm - so it's a bunch of stuff that comes together to do a job of some kind. The "stuff" can be people, ideas, computers, buildings or anything else - anything can be a component of the system.
So, here's an example of a computerised booking system for a health centre.
You can see the components within the system (the ovals), the boundary of the system (the line) and the idea of a subsystem.
One of the key ideas about systems is that they're connected. The components need to be linked together to perform the function of the network.
So, in the health centre booking example, the patient needs to be connected to the receptionist (via a telephone perhaps) who needs to be able to connect to a computer (via it's interface to access specific software I imagine).
Without connectedness systems aren't systems.
ICT systems basically do 3 things in some form:
- convey data - move it from one place to another
- manipulate data - change it from one form to another
- store data - so that it can be used at some other point
Another way of drawing this is as a flow diagram:
In this diagram User 1 keys the SMS message into their handset. The handset stores the message and manipulates it into a form which can be sent electronically (i.e. into binary code). The handset then connects to the SMS network and conveys the message to the message server where it is stored. The server then conveys the message to the receiving unit (perhaps via other parts of it's network) which stores and manipulates the data before alerting the user that they have a new text message.
The information will also be manipulated (and then stored) to work out how much to charge the users of the system - and data held on the server will be updated to reflect all of this.
There's the ICT system: components working together to convey, manipulate and store data to achieve an aim.