As usual, the goal is not to make a long-term network, but to explain basically what happens. And what happens can easily be summarized by the illustration of this Note (the header, as some say). A proxy is an intermediary computer foremost that you go to log on the internet. One wonders what it can be used to add an intermediary, but in fact it can be very useful.
Firstly in most companies the problem is privacy concerns. It must allow employees to connect to the internet to work, and prevent malware that enters the internal network of the company to spy information. To remedy this, which was done much until recently (now the problems of decentralization companies rise the problem to a higher degree of difficulty), it was to have one computer with internet connection that is encased in protective and whose access is restricted to the network administrator, and all employees’ computers that connect through it. Therefore the main computer acted as proxy.
There is also the issue of privacy on the Internet. When you go online, you leave a lot of traces, and tracing your IP address, you can connect a lot of information about you. Therefore the fact of going through a proxy can confuse the issue, as it is the IP address of the proxy that will be seen on the network.