The content of this article is to explain the interface ：  # Name name , The test plan has to have a name . # Comments Note , Except for the name , And let people know what it does . # User Defined Variables The test plan is the root node . The root node means that the domain of the work is global . ** User defined variables for test plan , It is used to set global variables **. On the interface , It shows a table , There are two columns , The first column is Name, The second column is Value, Corresponding to variable name and variable value respectively . At the bottom of the table is a row of buttons , Add, delete, modify, check and move the table up and down . After defining the variables , Through `${}` To use . For example, we define variables a The value is 1, Through ${a} To use . ** User defined variables , It's actually defined as a constant **.Value It's a string , What can't be changed . For example, we just defined variables a, Redefining variables b The value is ${a} + 1,b The actual value of is "${a} + 1", It doesn't work and it becomes 2. # Run Thread Groups consecutively Under the test plan , You can add multiple thread groups , Like this ：  Are these thread groups sequential or parallel ？ This is controlled by the test plan . If this option is checked , It's sequential execution , After the previous thread group has finished executing , Run the next thread group . If you don't check , It's parallel execution . Parallel execution is not sequential , The results are random . # Run tearDown Thread Groups after shutdown of main threads When a thread group is added , There's something else 2 Sort of thread groups ：  setUP Thread groups are used to initialize before testing ,tearDown Thread groups are used to clean up after testing . By default, this option is checked , Will execute tearDown Thread group . If it is not checked, it will not be executed . # Funtional Test Mode It's useless , Don't talk about it . # Add directory or jar to classpath At the bottom , You can add jar package or jar Package directory to classpath. What is classpath？ What is jar package ？ Therefore , I specially looked for Liao Xuefeng's Java course [classpath and jar](https://www.liaoxuefeng.com/wiki/1252599548343744/1260466914339296) Let's see . Explain briefly ,Java The original file is .java Archives , After compiling, it is .class Archives .JVM yes Java The actuator of , Can only execute .class Archives . In order to make JVM Find the one you want .class Archives , Need to put .class File path added to **classpath** in . For the convenience of management , Will put more than one .class File into a bag , Become a file , That is to say .jar Archives , be called **jar** package . JMeter Yes, it is Java The tools of writing , You can add jar Package to extend the functionality of the suite . One entrance is ** Test plan **, After all, it's a global root node , Very suitable . Another entry is to add the extension package , Put it directly into the installation directory **lib/ext** Under the catalogue . Recommend the latter . # A brief review of This paper is about JMeter The edit area of the test plan explains . The test plan is the only root node , Suitable for global configuration , For example, global variables , Control thread group execution mode , introduce ja