There are two ways to get access to the three models in the cloud explained above. When we say ‘in the cloud’, we may be talking about two different things: ‘public cloud’ or ‘private cloud’ - in other words, a public cloud environment or a private cloud environment. What’s the difference?
Well, most of the things we use ‘in the cloud’ are in what’s known as the public cloud: e-mail programs, data backup (and your holiday snaps) etc. You can compare the public cloud with a gigantic apartment building where you rent a little studio apartment, have your meals in a communal restaurant and work out in the basement gym. You don't have to take responsibility for maintaining the building, the caretaker does that. And all these services are simply included in the price you pay.
A private cloud, on the other hand, is like renting a whole house. You can split it up depending on your own wants and needs, but you also have to look after it a bit more. And you’re entirely responsible for the maintenance; if a domestic appliance ever needs replacing, you have to take care of it yourself. No to mention the security. However, the information you store there is always kept separate from your neighbours’.
You can easily run a business with servers, storage space or software application that exist solely in the public cloud, in other words are not actually present in your office. As mentioned, you lease everything from a third party: a host. With a private cloud, you yourself install the infrastructure for a group of users - in most cases, your employees. They then use the services that you’ve organised for them, and log into your network directly, with or without a VPN connection.