Lesson 8 of 8
Custom GPTs & Apps
7 min read
You've set up the same ChatGPT persona five times this week. What if you could build it once, name it, and even let it reach into real apps like your calendar?
Give it a ready-made skill
A [Custom GPT](glossary://custom-gpt) is ChatGPT, pre-set for one job. You give it instructions, some reference files, maybe a few example answers — no coding — then save it as "Recipe Helper" or "Legal Explainer" and reuse or share it. It's a Project you can hand to other people.
A Custom GPT packages your setup once so you — or anyone you share it with — start every chat ready to go.
Apps connect real services
Apps let ChatGPT reach outside itself — book a table, pull up a playlist, read your docs — by plugging into real services. They ride on MCP, one shared standard so any service can connect the same way, instead of a custom hookup for each. One port, many apps.
With Apps, ChatGPT stops being a talker and becomes a doer — it can act inside the services you connect, not just describe them.
An App can act on your behalf, so only connect ones you trust and read the permissions. "Read your email" and "send email as you" are very different powers to hand over.
The shape of it
- —A Custom GPT is ChatGPT pre-configured for one job, saveable and shareable.
- —Apps connect real services so ChatGPT can act, not just talk.
- —They use MCP — one standard — so any service plugs into the same port.
You want ChatGPT to actually book a table at a restaurant it found — not just tell you about it. What makes that possible?
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