OpenAI GPT

GPT (Generative Pre-trained Transformer) is the foundation of the modern AI revolution. In 2025, GPT-5 offers agentic capabilities, deep reasoning, and native multimodal integration.

When to Use

• General Purpose: It is the baseline for all AI tasks.
• Complex Reasoning: GPT-5 excels at multi-step logic and planning.
• Vision/Voice: Native "Omni" capabilities (GPT-4o/5) process audio and video with <300ms latency.

Core Concepts

Models

• GPT-5: The frontier model. Slow but smartest.
• GPT-4o: "Omni". Fast, multimodal, cheaper.
• o1 / o3: "Reasoning" models that "think" before answering (Chain of Thought).

Assistants API

Stateful API for building agents. Manages threads, retrieval (RAG), and code interpreter.

Structured Outputs

Guarantees JSON schema compliance for API responses.

Best Practices (2025)

Do:

• Use Structured Outputs: Always define a Zod/JSON schema for production apps.
• Use o3-mini for Code: It is cheaper and often better at coding than GPT-4o.
• Batch Requests: Use the Batch API for 50% discount on non-urgent tasks.

Don't:

• Don't use GPT-3.5: It is obsolete. Use GPT-4o-mini for cheap tasks.

References

• OpenAI API Documentation