Note: Introduced in GitSwarm 2016.2.
A pipeline is a group of builds that get executed in stages (batches). All of the builds in a stage are executed in parallel (if there are enough concurrent runners), and if they all succeed, the pipeline moves on to the next stage. If one of the builds fails, the next stage is not (usually) executed.
Builds are individual runs of jobs. Not to be confused with a build job or build stage.
Pipelines are defined in .gitlab-ci.yml by specifying jobs that run in stages.
See full documentation.
You can find the current and historical pipeline runs under Pipelines for your project.
Clicking on a pipeline will show the builds that were run for that pipeline.