> For the complete documentation index, see [llms.txt](https://docs.brigge.ai/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.brigge.ai/documentation/brigge-for-transformers/pipelines/pipeline-variables.md). # Pipeline variables ## Introduction A *variable* is a value that changes, based on information received at runtime. Once defined, variables can be referenced throughout Brigge - for example, in a [custom script](/documentation/brigge-for-transformers/pipelines/pipeline-nodes/custom-script-node.md), a [mapping transformation](/documentation/brigge-for-transformers/pipelines/pipeline-nodes/map-node.md), a [system parameter](/documentation/brigge-for-engineers/systems.md), etc. In Brigge, there are three variable types:
Variable typeSummaryReference syntax
SystemA standard set of variables that can be used to reference information about Brigge elements - for example, pipelines and environments.{{system.variable_key}}
Environment

Defined as part of environment setup. to be used.

Environment variables are a powerful way to define context-specific values for use across a range of pipeline steps. For example, you can set a metadata value to a resolved environment variable; define routes based on environment variables, output environment variable values to a set payload step for onward processing, etc.

{{env.variable_key}}
PayloadUser-defined variables, resolved from incoming payload values.{{payload.variable_key}}
Meta{{meta.variable_key}}
## System variables
NameDescriptionHow to useExample output
nowCurrent time as a Unix timestamp{{system.now}}1713091200
pipeline_idThe ID of the pipeline running{{system.pipeline_id}}9876
pipeline_nameThe name of the pipeline{{system.pipeline_name}}Sample Pipeline 1
pipeline_run_idThe ID of the current pipeline run{{system.pipeline_run_id}}12345
environmentThe name of the environment the pipeline is running in{{system.environment}}production
environment_idThe ID of the environment the pipeline is running in{{system.environment_id}}42