In order to start writing a Flink program, we first need to get an existing execution environment or create one. Depending upon what you are trying to do, Flink supports:
Getting an already existing Flink environment
Creating a local environment
Creating a remote environment
Typically, you only need to use getExecutionEnvironment(). This will do the right thing based on your context. If you are executing on a local environment in an IDE then it will start a local execution environment. Otherwise, if you are executing the JAR then the Flink cluster manager will execute the program in a distributed manner.
If you want to create a local or remote environment on your own then you can also choose do so by using methods such as createLocalEnvironment() and createRemoteEnvironment (String host, int port, String, and .jar files).