Google Gemini is a family of multimodal large language models by Google DeepMind, capable of understanding and generating text, images, audio, video, and code. As of May 2026, Gemini 3.5 Flash (released at Google I/O 2026) leads the stable lineup as the strongest agentic and coding model — outperforming Gemini 3.1 Pro on key benchmarks at 4× the speed of other frontier models — while Gemini 3.1 Pro Preview (2M token context) remains the flagship for deep reasoning. The API is accessible via two paths: the Gemini Developer API (API keys, Google AI Studio) and Vertex AI (enterprise GCP deployment with IAM). The official Python SDK is google-genai (pip install google-genai), offering both the classic generate_content and the new Interactions API (client.interactions.create()) designed for agentic workflows.
What This Cheat Sheet Covers
This topic spans 17 focused tables and 134 indexed concepts. Below is a complete table-by-table outline of this topic, spanning foundational concepts through advanced details.
Table 1: Model Variants
Each Gemini generation brings a different trade-off of intelligence, speed, and cost; choosing the right model — and knowing which are stable versus preview versus shutting down — is the single most important configuration decision in any Gemini project.
| Model | Example | Description |
|---|---|---|
model='gemini-3.5-flash' | • Current stable flagship — released May 19, 2026 (Google I/O 2026) • outperforms Gemini 3.1 Pro on coding and agentic benchmarks; 4× faster than other frontier models • 1M token context, 64K max output; thinking levels minimal/low/medium (default)/high• free tier available; Computer Use not yet supported. | |
model='gemini-3.1-pro-preview' | • Flagship for complex reasoning, multimodal, and vibe-coding tasks • 2M token context window — largest of any production model • thinking_level enum: LOW, MEDIUM, HIGH; no free tier• separate gemini-3.1-pro-preview-customtools endpoint for prioritizing custom tools. | |
model='gemini-3.1-flash-lite' | • Most cost-efficient stable model (GA May 7, 2026; replaces Preview) • optimized for high-volume agentic tasks, translation, simple data processing • free tier available; shutdown May 7, 2027. | |
model='gemini-3-flash-preview' | • Earlier-generation preview — recommended migration to gemini-3.5-flash• Agentic Vision: zooms, inspects, and manipulates images via code execution • thinking_level for latency control; free tier available; no shutdown date announced. |