Explain the key components of a GitLab CI pipeline.

A GitLab CI pipeline is made of stages, which run in order, and jobs, which do the work inside each stage. Each job runs a script on a runner.

• The pipeline is the top-level container for the whole CI/CD process on one commit.
• Stages are logical groups such as build, test and deploy, and they run sequentially.
• Jobs are the individual tasks inside a stage, and jobs in the same stage can run in parallel.
• Scripts are the shell commands each job executes.
• Runners are the agents that pick up jobs and execute them.

stages:
  - build
  - test
  - deploy

build-job:
  stage: build
  script:
    - echo "Building application"

test-job:
  stage: test
  script:
    - echo "Running tests"

In this pipeline, build-job runs first, and test-job starts only after the build stage finishes.