Justify why you would use the following: 

Intranet : An Intranet is a private computer network that is only accessible to authorised users on specific computers. Therefore intranets would be used by many organisation/businesses to allow users to share and view information. This information is then secure from outside users as only authorised users can access it. For example an intranet for a university may be offering many services that are available to students only. No one else on the web can access this information as they require the login details. Therefore you may choose to use an intranet as commercial or confidential information can be kept secure within an organisation, an intranet is very secure. There is no connection limits like the internet, and information specifically tailored to the organisations staff/students needs can be added/published that only they will be able to view.
Therefore, an intranet should be used within a school or organisation where information should only be available to students/staff and remain confidential. This is because an intranet can keep the network secure and allow only authorised users to gain access and view the confidential information. I would also use an intranet for schools/businesses because it will information to be shared with just authorised users,  for example chat rooms or email systems could;d be used within the intranet allowing employees to easily be able to share information with each other.

Extranet: An Extranet is where people from outside the organisation can connect to the internal intranet. For example, employees on business travel may use an extranet so they can still access information on their company's intranet. You could do this via two methods; through a mobile phone