An intranet is a web infrastructure within a company or organisation. It is usually protected from the outside world by a firewall and is only accessible to staff within the company or organisation.
There are a lot of benefits to having an intranet, such as better communications, file and documents sharing, and security. For example, if you are the health and safety officer within a company, you can place the health and safety regulations on the intranet for everyone to access.
Another example would be if you had to wait for someone from finance to come out of a meeting to get a timesheet; if it were on the intranet, you would be able to download it.
Intranets typically have internal e-mail systems set up so that staff can communicate using electronic mail instead of through memos and attending meetings.