What is a virtual private network (VPN)?

A virtual private network (VPN) is a secure network technology that allows users to send and receive data across public networks as if they were directly connected to a private network. This is accomplished by encrypting the data transmitted over the internet, which ensures that it is protected from eavesdroppers and hackers. VPNs create a secure "tunnel" through which data travels, granting privacy and anonymity for internet users. This feature is particularly important for individuals and organizations needing to safeguard sensitive information while using public Wi-Fi or accessing remote servers.

While the other options describe different networking concepts, they do not capture the essence of a VPN. For instance, a local network connecting multiple devices pertains to local area networking, not the secure transmission capabilities of a VPN. Similarly, a virtual environment for application testing relates to software development rather than secure data transmission. Lastly, a wired connection between computer systems does not encompass the capabilities of a VPN, which operates primarily over public internet networks. Thus, option A accurately defines a VPN by emphasizing its role in providing secure communication over public infrastructures.