What Is A Skill
Full Lesson Reference
What is a skill?
A skill is a reusable workflow packaged into a single command. Instead of explaining the same 20-step process to Claude every time you need a report, a campaign, or an audit, you write it once as a skill and invoke it with a slash command.
Skills are the single highest-leverage feature of Claude Code. This module is about using them and building them.
What a skill actually is
A skill is a SKILL.md file that lives at ~/.claude/skills/skill-name/SKILL.md. The file contains:
- Trigger - the slash command that invokes it (e.g. /wrapup)
- Description - a short summary of what the skill does + when to use it
- Instructions - the full workflow Claude follows when you trigger it
- Supporting files (optional) - templates, examples, reference data
When you type /skill-name, Claude loads the instructions and runs the workflow .
Why skills are transformative
Without skills, every task is explained from scratch. A 5-minute conversation to build a weekly report becomes a 5-minute conversation next time, and the time after, and every time after that.
With a skill, you write the instructions once. From then on, /weekly-report does the whole thing in 30 seconds. You become more valuable the more skills you have.
Range: simple to complex
Simple skill - just a markdown file
A 20-line instructions file. No supporting files. Example: /email-voice - "write emails in this voice: [description]".
Result: every email you ever write uses the same voice. Consistency across sessions.
Medium skill - instructions + reference
Instructions + example files. Example: /weekly-report - "build a report following this template with this brand using this data sources".
Result: every weekly report comes out structurally identical, on-brand, with correct data sources.
Complex skill - instructions + data + scripts
Multi-step workflow with multiple files. Example: /full-audit - "pull data from 5 platforms, run 12 analyses, generate HTML, encrypt, deploy, notify team".
Result: a 3-day deliverable ships in 30 minutes.
3 ways skills get triggered
- Slash command (explicit)
/weekly-report client-name
You invoke it directly. Fast, explicit. 2. Natural language (implicit)
Build me the weekly report for client-name
Claude recognises the intent and triggers the skill automatically. Only works if Claude knows the skill is relevant from its description.
- Automatic (via triggers)
Some skills self-invoke when certain conditions are met. Example: a data-integrity skill might run automatically whenever Claude is about to include metrics in a deliverable.
When skills beat raw prompting
- You've done the same task 3+ times
- Consistency matters (same format, same brand, same structure)
- The task has multiple steps you always forget one of
- You want to share the workflow with your team
- You want to batch-run the workflow (automate it later)
When NOT to build a skill
- One-off tasks you won't repeat
- Tasks that change every time based on inputs (less repeatable)
- Tasks simple enough that the prompt is the skill
- Before you've done the task manually enough to know what the shape is
Action items
☐ Understand: a skill = SKILL.md with trigger + description + instructions
☐ Know the 3 trigger types: slash command, natural language, automatic
☐ Start a mental list - what tasks do you repeat most? Those are skill candidates. Next lesson: Using the skills library.
Exercises
- Review the concepts covered in this lesson: What Is A Skill.
- Write down your key takeaway from this lesson.
- Practice running any commands or prompts mentioned above inside your terminal.