An Execution Environment refers to the context in which a program or application runs. It includes the hardware, operating system, and any necessary software libraries that support the execution of code. This environment ensures that the program has access to the resources it needs, such as memory and processing power, to function correctly. Different types of execution environments exist, such as local environments on personal computers and cloud-based environments like Amazon Web Services or Microsoft Azure. Each environment can have unique configurations and limitations, affecting how applications perform and interact with other systems.