The short version
| Prompt | Custom GPT or Gem | AI skill | |
|---|---|---|---|
| What it is | Words you type in the chat | A separate chatbot with its own instructions | A folder of instructions your AI opens when needed |
| Where it lives | In your head, or a notes file | Inside one app | In your AI app, and works across many apps |
| When it's used | Only when you paste it | Only when you open that chatbot | Automatically, when your request matches |
| Can include files and scripts | No | Files, yes | Files and scripts |
| Updates | You edit it yourself | You edit it yourself | The maker ships new versions |
| What's next | Still useful | Custom GPTs retire on 11 December 2026. Gems are turning into skills | The way most AI apps are heading |
Prompts
A prompt is simply what you type. Good prompts help a lot, and you should keep writing them. The catch is that you have to remember the good ones, paste them every time, and you only ever get your own know-how.
Custom GPTs are retiring
A custom GPT is a chatbot set up inside ChatGPT with its own instructions and files. OpenAI is retiring them on 11 December 2026. FedRAMP workspaces, and Enterprise workspaces with an approved deferral, have until 11 February 2027. Personal accounts (Free, Go, Plus and Pro) already can't create new GPTs, and OpenAI moves a GPT's instructions into a skill. So don't start a new GPT now: use a skill.
Gems are turning into skills
A Gem is Gemini's version of the same idea. On personal Google accounts, Google turns Gems into skills from November 2026. Each moved skill keeps its name, instructions and files, and you check it and turn it on. Business accounts follow no sooner than 1 March 2027, and education accounts no sooner than 1 June 2027. Until then, work and school accounts can keep using Gems.
AI skills
A skill is know-how your own AI opens by itself. You keep chatting in one place, and the AI pulls in the right skill for the job: the listing skill for a listing, the tax skill for your tax return. Because skills follow an open standard, the same skill can work in Claude, ChatGPT, Gemini, Microsoft 365 Copilot, GitHub Copilot, Cursor and more.
Skills can also carry examples, templates and small scripts, so they can do things a prompt can't, like run a calculation the same way every time.
What about Projects?
A Project (in ChatGPT or Claude) keeps instructions and files that apply to every chat inside it. That makes it a handy place to paste a short copy of a skill when your app or plan can't take the real thing. Some skills on Trilly come with a Project version for exactly this. A pasted copy won't update, and Trilly can't count it in the skill's public numbers.
Which should you use?
- One-off question: type a prompt.
- A job you do every week: use a skill, so your AI does it the same good way each time.
- Your app or plan can't take skills: paste the skill's Project version, or its Gem version on a work or school Google account (Trilly offers Gem versions up to 1 June 2027). Our guides for ChatGPT and Gemini show how.
New to all this? Start with what an AI skill is, then browse skills for your job.