As far as business network infrastructure is concerned, there are three broad categories of networks, namely the Internet, intranet, and extranet. we will discuss the two as follows 
1)internet

2)intranet

INTERNET: Internet is a global system of interconnected computer networks. It is not controlled by a central entity and therefore relies on network devices and accepted conventions and protocols to relay the data traffic until it gets to its destinations. 

INTRANET:Intranet is a private network that is setup and controlled by an organization to encourage interaction among its members, to improve efficiency and to share information, among other things. Information and resources that are shared on an intranet might include: organizational policies and procedures, announcements, information about new products, and confidential data of strategic value.