What is a common characteristic of computers connected to the Internet?

A common characteristic of computers connected to the Internet is that they have unique IP addresses. Each device on the Internet is assigned an Internet Protocol (IP) address, which serves as a unique identifier that allows it to communicate with other devices and access resources across the network. This uniqueness is essential for routing data correctly, as it ensures that information sent over the Internet reaches the appropriate destination without confusion.

Devices can belong to various networks and use different software applications, so assumptions that they are all part of a single network or operate on the same software are not accurate. Additionally, while sending emails is a function of many Internet-connected devices, it is not a defining characteristic, as these computers can perform a wide variety of other tasks as well. Thus, the uniqueness of IP addresses stands out as the correct defining trait.