Writing templates using the Twig language. Reviewing other people's templates.
Demonstrated by: 

A Skilled Twig coder should be able to do the following:

An Expert Twig coder should additionally be able to do the following:

Roles and Tasks that may use this skill

Accessibility group member (Contributor role)
Improve the accessibility of Drupal core and contributed modules, themes, and distributions
Duration: ongoing
Backport a patch (Contributor task)
After a patch has been committed to the latest development version of a project, adapt it for an earlier version
Duration: 1 hour
Create a merge request for an issue (Contributor task)
Add or update a "merge request" (software fix) on an issue
Duration: 1 hour
Drupal Core Leadership Team (Contributor role)
Perform final review and governance on community-suggested improvements to Drupal core
Duration: ongoing
DrupalCamp speaker (Contributor role)
Make a presentation at a DrupalCamp or DrupalCon event
Duration: 1 hour
Mentor (Contributor role)
Inspire, enable, and encourage new core contributors. Work on the core tools and process for mentoring
Duration: several hours
Write a change record for a Drupal core issue (Contributor task)
Create a page that documents a change made to Drupal core on an issue.
Duration: 20 minutes