🟢 ChatGPT & GPT Mastery
Learn ChatGPT & GPT Mastery on AI4AI — short, hands-on lessons with live AI runs, at three reading levels (beginner to expert). Free to start.
What you'll learn
- Picking the Right GPT: Model Families in 2026 (7 min) — ⚡ By mid-2026, OpenAI's production lineup has settled into three practical tiers. GPT-5 class models (including GPT-5 a…
- Custom Instructions & Memory: Make ChatGPT Remember You (7 min) — ⚡ By default, ChatGPT has no persistent state — every new conversation starts with a blank context window. Two features…
- Structured Outputs & JSON Mode: Machine-Readable Answers from GPT (8 min) — When building apps or automations that consume GPT output, free-form prose is fragile — your code has to parse unpredic…
- Function Calling & Tools: GPT as an Action-Taker (8 min) — Function calling (also called tool use) lets GPT models pause mid-response, invoke a named function you define, receive…
- Custom GPTs & the Assistants Approach: Building Reusable AI Experts (8 min) — A Custom GPT (available in ChatGPT) and an OpenAI Assistant (built via the Assistants API) are two surfaces for the sam…
- Vision, Voice & Image Generation: GPT's Multimodal Powers (8 min) — GPT-4o and later models are multimodal, meaning a single model handles text, images, and audio in one unified system ra…
Lessons
Picking the Right GPT: Model Families in 2026
⚡ By mid-2026, OpenAI's production lineup has settled into three practical tiers. GPT-5 class models (including GPT-5 and GPT-5-turbo) sit at the top: they excel at multi-step reasoning, complex coding, research synthesis, and tasks requiring long coherent context. They cost rou…
Custom Instructions & Memory: Make ChatGPT Remember You
⚡ By default, ChatGPT has no persistent state — every new conversation starts with a blank context window. Two features fix this for ChatGPT users. **Custom Instructions** (Settings → Personalization → Custom Instructions) let you store up to ~1,500 characters in two fields: (1)…
Structured Outputs & JSON Mode: Machine-Readable Answers from GPT
When building apps or automations that consume GPT output, free-form prose is fragile — your code has to parse unpredictable text. JSON mode (and the newer Structured Outputs feature) solve this by constraining GPT to return valid, machine-readable JSON every time. **JSON mode**…
Function Calling & Tools: GPT as an Action-Taker
Function calling (also called tool use) lets GPT models pause mid-response, invoke a named function you define, receive the result, and then continue generating. The model never actually executes code itself — it emits a structured JSON payload describing which function to call …
Custom GPTs & the Assistants Approach: Building Reusable AI Experts
A Custom GPT (available in ChatGPT) and an OpenAI Assistant (built via the Assistants API) are two surfaces for the same core idea: packaging a system prompt, optional knowledge files, and optional tools into a persistent, shareable configuration so you don't re-explain context …
Vision, Voice & Image Generation: GPT's Multimodal Powers
GPT-4o and later models are multimodal, meaning a single model handles text, images, and audio in one unified system rather than stitching separate models together. Vision input lets you upload screenshots, charts, PDFs rendered as images, or photos and ask the model to read, de…