> ## Documentation Index
> Fetch the complete documentation index at: https://docs.projectdiscovery.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Variables

> Review details on variables for Nuclei

Variables can be used to declare some values which remain constant throughout the template. The value of the variable once calculated does not change. Variables can be either simple strings or DSL helper functions. If the variable is a helper function, it is enclosed in double-curly brackets `{{<expression>}}`. Variables are declared at template level.

Example variables -

```yaml theme={null}
variables:
  a1: "test" # A string variable
  a2: "{{to_lower(rand_base(5))}}" # A DSL function variable
```

Currently, `dns`, `http`, `headless` and `network` protocols support variables.

Example of templates with variables -

```yaml theme={null}
# Variable example using HTTP requests
id: variables-example

info:
  name: Variables Example
  author: pdteam
  severity: info

variables:
  a1: "value"
  a2: "{{base64('hello')}}"

http:
  - raw:
      - |
        GET / HTTP/1.1
        Host: {{FQDN}}
        Test: {{a1}}
        Another: {{a2}}
    stop-at-first-match: true
    matchers-condition: or
    matchers:
      - type: word
        words: 
          - "value"
          - "aGVsbG8="
```

```yaml theme={null}
# Variable example for network requests
id: variables-example

info:
  name: Variables Example
  author: pdteam
  severity: info

variables:
  a1: "PING"
  a2: "{{base64('hello')}}"

tcp:
  - host: 
      - "{{Hostname}}"
    inputs:
      - data: "{{a1}}"
    read-size: 8
    matchers:
      - type: word
        part: data
        words:
          - "{{a2}}"
```