# User-Defined Variables

The Variables section is a key-value storage for storing and reusing some data. It is often used for removing code duplicates and improving readability: the greetingUrl variable says more than just the line <https://next.json-generator.com/api/json/get/EJvQVEVGL> for sure.

The variables mechanism is very well integrated to all application parts and has several features:

* You can use strings, objects, arrays, and links to other variables as values.
* Variables are defined for each node and are inherited from parent nodes.
* Variables values can refer to other variables.
* [Default variables](https://docs.testmace.com/variables/variables) names start with $.

### Using Variables

You can use variables in any string parameters of the node - URLs, headers names, authorization tokens, etc. To do that, use the `${variableName}` syntax, where `variableName` is a link to the variable. Here are some examples:

* `${id}`
* `${$dynamicVar.id}`
* `${$response.body.name}`

It's possible to combine strings and links to other variables in the node parameters fields. For instance, you can use  `http://${host}/posts/${$dynamicVar.id}` as an URL.&#x20;

To access an array element, that is stored in a variable, you can use the `${variableName[index]}` syntax. For example, to access the third response entity id, you'll write `${$response.body[2].id}`. Note that it the index is zero-based.

Autocompletion works for variables:

![](https://gblobscdn.gitbook.com/assets%2F-Lh_FaVh9XfQJ0p1KqZ1%2F-MEY9ibfnYvDKaURxlxy%2F-MEY9mDK7gTKvDfOGiWm%2Fvariables1.gif?alt=media\&token=3a1d85be-cefd-4daf-ae05-57107f4c3b4b)

Variable value highlighting works as well:

![](https://gblobscdn.gitbook.com/assets%2F-Lh_FaVh9XfQJ0p1KqZ1%2F-MEY9ibfnYvDKaURxlxy%2F-MEYAHlXOuh-KHuhndW9%2FScreenshot%202020-08-12%20at%2018.57.17.png?alt=media\&token=1a488086-2e8c-4597-999f-513c474ccfb0)

There is the Variables tab in every node interface, that contains the variables list. This is how the tab looks like:

![](https://gblobscdn.gitbook.com/assets%2F-Lh_FaVh9XfQJ0p1KqZ1%2F-MEY9ibfnYvDKaURxlxy%2F-MEYAgxCEmpEv54HZrYP%2FScreenshot%202020-08-12%20at%2018.58.23.png?alt=media\&token=0bacf5d4-f58c-4055-8033-bdcef09631f7)

The tab looks the same for all node types. You'll learn more about how to work with variables in the next sections.