A Run-Time Environment is a collection of resources and services that a computer program uses while it is executing. It provides the necessary support for the program, including memory management, input/output operations, and access to system resources. This environment ensures that the program runs smoothly and efficiently, handling tasks like variable storage and function calls. In programming, different languages have their own specific run-time environments, such as the Java Virtual Machine for Java applications or the Common Language Runtime for C#. These environments help manage the execution of code, allowing developers to focus on writing programs without worrying about the underlying hardware details.