The Complete Google Gemini Guide 2025: All 8 Models, 6 Power Tools & 15 Practical Use Cases

Google Gemini has evolved into the most comprehensive AI ecosystem as of December 2025. With 8 specialized models, 6 powerful tools, and the new Interactions API, Gemini offers more capabilities than ever before.

The problem: Most users only utilize a fraction of these features. They type in questions, get answers – and miss 90% of the potential in the process.

This guide changes that. Here you'll learn not only which models and tools exist, but when to use which one and how to achieve maximum results with precise prompts.

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Part 1: Understanding the 8 Gemini Models & Modes

Gemini is not one model, but a family of specialized AI systems. The right choice saves time, money, and delivers better results.

Gemini 3 – The Multimodal Flagship

Optimized for: State-of-the-art logic and reasoning

Gemini 3 is the heart of the family. As a multimodal model, it processes text, code, images, video, and audio in a single context. Its knowledge extends through January 2025.

When to use:

• Complex tasks that combine multiple media types
• Analysis of documents with images and text
• Code reviews with visual diagrams

Specifications:

• 1,048,576 token input context
• Up to 65,536 tokens output
• Multimodal: Text, image, video, audio, PDF

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Fast – Speed for Everyday Tasks

Optimized for: Quick responses to everyday tasks

Fast mode combines PhD-level reasoning with lightning-fast response times. Ideal for tasks where speed is more important than in-depth analysis.

When to use:

• Quick research
• Simple text generation
• Brainstorming sessions
• Frequently recurring tasks

How to activate Fast:

Select "Fast" in the Gemini app dropdown.

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Thinking – When Logic Counts

Optimized for: Instruction following and verified answers

Thinking mode activates a dedicated reasoning layer. You'll see "Thinking..." while Gemini builds a chain of thought, verifies logic, and plans multi-step solutions.

The thinking_level parameter:

When to use:

• Tasks with multiple steps
• When hallucinations must be avoided
• Verifiable facts required

Prompt tip:

Analyze this data step by step. Show your reasoning 
before drawing a conclusion.

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Pro – For the Toughest Problems

Optimized for: Complex problem-solving, scientific analysis

Gemini 3 Pro is the highest performance tier for demanding coding tasks, scientific analysis, and "unsolvable" mathematical problems.

When to use:

• Advanced coding and debugging
• Scientific paper analysis
• Complex logical puzzles
• Architecture decisions

Cost (API):

• $2 per 1M input tokens
• $12 per 1M output tokens

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Deep Think – Parallel Reasoning for Maximum Accuracy

Optimized for: Step-by-step logic, proofs, mathematical puzzles

Deep Think is a specialized mode that builds on top of Gemini 3 Pro. Instead of simply generating longer responses, Deep Think executes parallel reasoning threads, compares hypotheses, and consolidates them into a final answer.

Benchmark performance:

• 92% success rate on multi-step logic puzzles (vs. 76% standard)
• 41.0% on Humanity's Last Exam (without tools)
• 45.1% on ARC-AGI-2 (with code execution)

When to use:

• Mathematical proofs
• Complex logic puzzles
• Strategic planning
• Scientific problem-solving

How to activate Deep Think:

1. Select "Deep Think" in the prompt bar
2. Choose "Thinking" in the model dropdown
3. Send your request – responses take several minutes

Availability: Google AI Ultra subscription required

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Imagen 4 – Photorealistic Image Generation

Optimized for: Visually high-quality, realistic images

Imagen 4 creates photorealistic assets, perfect text rendering in images, and high-resolution graphics.

When to use:

• Marketing visuals
• Product images
• Realistic scenes
• Stock photo alternatives

Prompt example:

Generate a photorealistic image of [subject].

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Nano Banana Pro (Gemini 3 Pro Image) – Interactive Image Editing

Optimized for: Multi-turn image editing with conversation

Nano Banana Pro, officially known as Gemini 3 Pro Image, is Google's most advanced model for image generation and editing. It enables conversational, iterative image editing.

Key features:

• Up to 4K resolution
• Perfect text rendering in images
• 14 reference images simultaneously (logos, color palettes, product photos)
• Multi-turn editing: "Make the sky bluer", "Add a person"

When to use:

• Brand-consistent visuals
• Iterative design
• Text-in-image generation
• Product variations

Availability: Gemini App (Desktop & Mobile), AI Mode in Search, NotebookLM, Slides, Vids

Prompt example:

Create a marketing banner for [product]. 
Use this color palette: [Upload reference image]
Add the text: "Save 20% Now"

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Veo 3.1 – Cinematic Video Creation

Optimized for: High-fidelity 4K video with synchronized audio

Veo 3.1 generates cinematic video clips with lighting, SFX, and synchronized dialogue. A game-changer for video content without production overhead.

Key features:

• 4K resolution
• Native audio with SFX
• Synchronized dialogue
• Cinematic lighting

When to use:

• Social media videos
• Product demos
• Explainer videos
• Marketing clips

Prompt example:

Create a cinematic video of [scene] with ambient sound.

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Part 2: The 6 Gemini Power Tools in Detail

Beyond the models, Gemini offers specialized tools for recurring workflows.

Gemini Gems – Your Personal AI Experts

What it does: Creates custom, reusable AI assistants

A Gem is a customized Gemini version with predefined instructions. Instead of entering the same context information in every chat, you create a Gem once and use it permanently.

When to use:

• Recurring tasks with specific requirements
• Role-based assistants (Coding Coach, Marketing Expert)
• Team workflows with consistent standards

How to create a Gem:

1. Go to gemini.google.com
2. Click on "Explore Gems"
3. Select "Create New Gem"
4. Enter name, description, and detailed instructions
5. Optional: Upload up to 10 reference files (Knowledge feature)

Pro tip: Use the Magic Wand icon to have Gemini expand and refine your instructions.

Example Gems:

• Coding Coach: Explains code, suggests best practices
• Content Editor: Checks texts for style and grammar
• Research Assistant: Structures research systematically

Prompt for Gem creation:

Name: SEO Content Writer
Description: Writes SEO-optimized blog posts

Instructions:
- Integrate keywords naturally into the text
- Use H2 and H3 headings
- Write in active voice
- Each paragraph max. 3 sentences
- Add a meta description at the end

Availability: Gemini Advanced or Gemini for Workspace

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Deep Research – Autonomous Research Engine

What it does: Automatically browses hundreds of websites and creates multi-page reports

Deep Research is an autonomous agent that transforms your query into a research plan, searches the web, analyzes PDFs, evaluates data tables, and even accesses your Gmail, Drive, and Chat (with permission).

The process:

1. Automatically creates a multi-point research plan
2. Autonomously browses hundreds of websites
3. Shows its thinking process during iteration
4. Resolves contradictions through additional sources
5. Delivers structured reports with citations

When to use:

• Complex research topics
• Market analyses
• Literature reviews
• Competitive analyses
• Due diligence

Benchmark performance:

• 46.4% on Humanity's Last Exam
• 66.1% on DeepSearchQA
• 59.2% on BrowseComp

How to use Deep Research:

1. Click on "Tools" in the prompt bar
2. Select "Deep Research"
3. Enter your research question
4. Wait for the report (several minutes)

Output options:

• Google Canvas (interactively editable)
• PDF export
• Audio Overview (as podcast)

Prompt example:

Write a comprehensive report on [topic] and cite all sources.

Availability: Gemini Advanced ($20/month)

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Canvas – Real-Time Collaborative Work

What it does: Split-screen workspace for writing and coding with AI

Canvas is an interactive workspace where you create and edit documents or code side by side with Gemini. Changes appear in real-time.

Key features:

• "Show, don't just tell" – see changes live
• Dedicated editor for docs and code
• Iterative refinement
• Export options

When to use:

• Create and refine documents
• Write and debug code
• Create infographics
• Develop presentations

How to use Canvas:

1. Select "Canvas" in the prompt bar
2. Describe what you want to create
3. Edit in split-screen

Prompt examples:

For documents:

Create a business plan for a SaaS startup in the [niche] space.

For code:

Create a prototype for a [type] web app.

For infographics:

In Canvas: Create an infographic that summarizes this data.

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Audio Overview – Documents as Podcasts

What it does: Transforms documents into engaging audio discussions between two AI hosts

Audio Overview transforms dry documents into podcast format – perfect for learning on the go or when you don't have time to read.

When to use:

• Consume long documents
• Learn while commuting
• Understand complex reports
• Process meeting notes

How to use Audio Overview:

1. Upload a document or slides
2. Click on "Audio Overview"
3. Listen to the generated discussion

Prompt example:

Upload: [PDF/Document]
→ Click "Audio Overview"
→ Automatically generates a discussion

Formats: Google Docs, PDFs, Slides

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Gemini Live – Hands-Free Conversation with Vision

What it does: Real-time voice chat that can "see" through your camera

Gemini Live is an interruptible voice chat that captures your environment via camera. The latest updates bring Visual Guidance – Gemini highlights objects directly on your screen.

Key features:

• Real-time voice chat
• Camera and screen sharing (now free)
• Visual Guidance: Objects are marked on screen
• App integrations: Maps, Calendar, Tasks, Keep
• Emotional voice adaptation: Tone adjusts to conversation topic

When to use:

• Mobile/hands-free help
• Technical support with camera
• Styling advice
• Home improvement projects
• Learning with visual support

Availability:

• Free for everyone on Android and iOS
• Visual Guidance from August 2025 (Pixel 10+, then Android, then iOS)

Example applications:

"What do you see through my camera?" 
→ Show a product for recommendations

"Help me assemble this IKEA shelf"
→ Point camera at the parts

"What kind of plant is this?"
→ Real-time identification

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Guided Learning – Your Personal Learning Coach

What it does: Interactive learning companion with study guides, flashcards, and quizzes

Guided Learning turns Gemini into a tutor. Instead of simply providing answers, it asks questions, explains concepts step by step, and tests your knowledge with interactive quizzes.

Key features:

• Step-by-step explanations
• Adaptation to your understanding level
• Automatic study guides
• Flashcard generation
• Interactive quizzes with hints and explanations
• Visual aids: Diagrams, videos

When to use:

• Learn a new topic
• Exam preparation
• Deepen concepts
• Understand complex topics

How to activate Guided Learning:

1. Toggle "Guided Learning" in the prompt bar
2. Ask your learning question
3. Interact with quizzes and explanations

Prompt examples:

Create a study guide on [topic].

Quiz me on [topic] with multiple-choice questions.

Explain [concept] to me step by step, as if I were a beginner.

Technology: Powered by LearnLM – Google's learning-optimized model

Availability: Guided Learning for all ages. Quizzes, flashcards, study guides for 18+.

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Part 3: 15 Practical Applications with Exact Prompts

Here are concrete use cases with the tools and prompts you can use directly.

1. Transcribe Video to Text

Tool: Uploads

Prompt:

Transcribe this video and keep everything intact.

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2. Audio to Text with Timestamps

Tool: Uploads

Prompt:

Transcribe verbatim with timestamps and speaker identification.

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3. Create Infographics

Tool: Canvas

Prompt:

In Canvas: Create an infographic that summarizes this data:
[Insert data]

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4. Generate Podcast from Document

Tool: Audio Overview

Action:

Upload: [Document/Slides]
→ Click "Audio Overview"
→ Automatic discussion between two AI hosts

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5. Build Web App Prototype

Tool: Canvas

Prompt:

Create a prototype for a [type] web app.

Canvas visualizes the code in real-time.

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6. Generate Cinematic Video

Tool: Veo 3.1

Prompt:

Create a cinematic video of [subject] with ambient sound.

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7. Create Photorealistic Images

Tool: Imagen 4

Prompt:

Generate a photorealistic image of [subject].

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8. Deep Research Report

Tool: Deep Research

Prompt:

Write a comprehensive report on [topic] and cite all sources.

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9. Create Custom Gem

Tool: Gem Manager

Action:

Gem Manager → "Create New" → Add instructions

Example instructions:

You are a coding coach for Python. 
- Explain concepts with simple examples
- Suggest best practices
- Give constructive feedback on code

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10. Workspace Actions (Find Email, Update Calendar)

Tool: Extensions

Prompt:

Find the email from [name] and add the deadline to my calendar.

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11. Guided Learning – Master a Topic

Tool: Learn Mode

Prompt:

Upload: [Notes/Documents]
→ "Create a study guide and quiz me on it."

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12. Create Children's Book

Tool: Gems + Canvas

Prompt:

Create a picture book about [topic] for a 5-year-old child.

Then: Export as PDF

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13. Create Quiz

Tool: Canvas

Prompt:

Upload: [Learning material]
→ "Create a multiple-choice quiz on this topic."

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14. Code Review with Explanation

Tool: Canvas + Thinking Mode

Prompt:

Analyze this code for:
1. Bugs and errors
2. Performance issues
3. Best practice violations

Explain each problem and show the solution.

[Insert code]

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15. Marketing Visuals with Brand Consistency

Tool: Nano Banana Pro

Prompt:

Create a social media banner for [campaign].
References: [Upload logo, color palette, product photo]
Text on the image: "[Slogan]"

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Part 4: Gemini for Developers – APIs & Pricing

Interactions API (Beta since December 2025)

The Interactions API is a unified interface for Gemini models and agents. It simplifies state management, tool orchestration, and long-running tasks.

Key features:

• Server-side conversation state management
• Background execution for long-running tasks
• Remote MCP tools integration
• Structured JSON outputs
• Native streaming

Code example:

from google import genai

client = genai.Client()

# Standard Model Call
response = client.interactions.create(
    model="gemini-3-pro-preview",
    messages=[{"role": "user", "content": "Explain quantum computing"}]
)

# Deep Research Agent
response = client.interactions.create(
    agent="deep-research-pro-preview-12-2025",
    messages=[{"role": "user", "content": "Research report on AI Agents 2025"}],
    background=True  # For long-running tasks
)

Pricing Overview (API)

Consumer Pricing

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Part 5: Gemini vs. ChatGPT vs. Claude – When to Use Which?

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FAQ: Frequently Asked Questions

What's the difference between Gemini 3 Flash and Pro?

Flash offers Pro-level intelligence at Flash pricing ($0.50 vs $2 per 1M input tokens). Pro is optimized for the most complex problems and delivers more in-depth analyses.

For 90% of use cases, Flash is sufficient.

Is Gemini free?

Yes, the basic version is free. For Deep Research, Deep Think, and higher usage limits, you need Gemini Advanced ($19.99/month).

What's the difference between "Thinking" and "Deep Think"?

"Thinking" is a mode that increases reasoning depth (adjustable via thinking_level). "Deep Think" is a separate, specialized mode that executes parallel reasoning threads – significantly slower, but unmatched for mathematical proofs and complex logic.

Can Gemini access my Google Drive and Gmail?

Yes, with permission. Deep Research can access Gmail, Drive, and Chat to conduct personalized research.

You control the access permissions.

What prompts work best with Gemini?

Use the 5-part framework: Role, Goal, Inputs, Constraints, Output Format. The more specific, the better.

Example:

Role: You are an SEO expert
Goal: Analyze this website for ranking factors
Input: [URL]
Constraints: Focus on technical SEO
Output: Bullet-point list with priorities

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Conclusion: Your Gemini Workflow

Google Gemini is more than a chatbot – it's an ecosystem of specialized models and tools. The key lies in choosing the right tool for the right task.

Quick reference:

December 2025 was a turning point for AI tools. With the Interactions API and the Deep Research Agent, Google has laid the foundation for autonomous AI workflows.

The tools exist. The only question remaining is: What will you build with them?

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Written by Michael Kerkhoff, Founder of Context Studios UG.

Sources:

• Gemini 3 Flash Launch
• Gemini Deep Think
• Nano Banana Pro
• Interactions API
• Gemini Deep Research
• Gemini Live Updates
• Guided Learning
• Gemini Gems

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