This is the root element of the JMeter scripts and houses the other components such as Threads, Config Elements, Timers, PreProcessors, PostProcessors, Assertions, and Listeners. It also offers a few configurations of its own.

First off, it allows you to define user variables (name-value pairs) that can be used later in your scripts. It also allows the configuration of how the thread groups that it contains should run, that is, should thread groups run one at a time? As test plans evolve over time, you'll often have several thread groups contained within a test plan. This option allows you determine how they run. By default, all thread groups are set to run concurrently. A useful option when getting started is the Functional...