A virtual private network (VPN) is a technology to connect computer systems with remote computer networks by using the Internet or another intermediate network. In other words, A VPN is a private network that uses a public network to connect remote sites or users together. The VPN uses "virtual" connections routed through the Internet from the business's private network to the remote site or employee.

VPNs can connect individual users to a remote network or connect multiple networks together.
For example, users may use a VPN to access their office system from home.

Through VPNs, users can access resources on remote networks, such as files, printers, databases, or some internal websites. VPN remote users will be under the impression of being directly connected to the central network via a point-to-point link.

Early networks allowed VPN-style remote connectivity through dial-up modems or through leased lines. IP-VPNs have become more prevalent due to significant cost-reductions, increased bandwidth, convenience and security.

Types of VPN
VPNs can be either
1. Remote-Access (connecting an individual computer to a network) - In a corporate setting, remote-access VPNs allow employees to access their company's intranet from home or while traveling outside the office.

2. Site-To-Site (connecting two networks together) - Site-To-Site VPNs allow employees in geographically separated offices to share one cohesive virtual network. A VPN can also be used to interconnect two similar networks over a dissimilar middle network; for example, two IPv6 networks over an IPv4 network.

Advantages of VPN
As a business grows, it might expand to multiple offices across the country and world. To keep things running efficiently, employees of the company need a fast, secure and reliable way to share information across computer networks.
Advantages of VPN are:

Security-When you connect to the network through a VPN, the data is kept secured and encrypted.

Remote Access -
The main advantage of having a VPN is that the information can be accessed remotely even from home or from any other place. That’s why a VPN is useful for companies and can increase productivity within a company.

Sharing of files –
We can use VPN service to share files, data etc.

Unblock websites & bypass filters-
VPNs are great for accessing blocked websites or for bypassing Internet filters. This is why there is an increased number of VPN services used in countries where Internet censorship is applied.

Improved performance-
Bandwidth and efficiency of the network can be generally increased once a VPN solution is implemented.

Reduced costs-
Once a VPN network is created, the maintenance cost gets reduced considerably.