> For the complete documentation index, see [llms.txt](https://docs.ddosify.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.ddosify.com/ddosify/performance-testing/correlation.md). # Correlation {% embed url="" %} Correlation allows you to link steps together. For instance, you can design a test scenario to evaluate your authentication process by taking the following steps: First, obtain the authentication token from the response of a login request. Then, insert the extracted token into subsequent requests. This short example demonstrates how correlation works in practice. #### Capture Value from the Response 1. Click the ***More*** button located to the right of the step and open the "Step Details" section.

2. To capture a value from the response of a step, go to the "Capture" tab in the "Step Detail" section and follow these steps: * Give a unique name to a variable that you will use to access the captured value in subsequent requests. * Select whether to extract the value from the response body or response headers. * Choose the appropriate extraction type based on where you extract the value. * If you're extracting from the response body, you can use JSON path, XML path, or regular expressions to extract the value. * If you're extracting from response headers, you can extract the entire header value or a part of the header value by using regular expressions.

#### Use Captured Value in Requests You can use the format {{captured\_variable\_name}} to insert a value that was previously captured into various parts of subsequent requests. This includes the URL, the request body, query parameters, headers, and authentication information.