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AI Basics - AI Model Categories with Examples and Capabilities

[Last Updated: Jan 18, 2026]

AI Model Categories refer to the systematic classification of artificial intelligence systems based on their architecture, function, and capabilities. They group models by their design approach—such as neural networks, decision trees, or generative models—which dictates how they process data and solve tasks. This categorization helps researchers and developers compare methods, choose the right tool for specific problems, and understand the field's technological landscape.

1. Text (Language-Only) Models

These models accept text input and produce text output. They focus on natural language understanding and generation.

Actively Used

GPT-4.1 / GPT-5.x family – General-purpose language models used in production systems.

Claude 3 (Sonnet, Opus) – Widely used for reasoning-heavy and enterprise workloads.

Gemini 2.x / 3.x – Google’s flagship language and multimodal models.

LLaMA 3 / LLaMA 4 – Popular open-weight models for self-hosted and research use.

Largely Obsolete / Legacy

GPT-3 / GPT-3.5 – Superseded by newer generations; rarely used in new systems.

Original GPT-4 (2023) – Replaced by GPT-4o and GPT-4.1 variants.

2. Vision Models

These models analyze images without direct language generation capabilities.

Actively Used

YOLO (v8+) – Real-time object detection in production pipelines.

Modern ViT-based backbones – Used internally within multimodal systems.

Largely Obsolete / Legacy

ResNet (standalone usage) – Mostly retained for academic reference.

3. Vision–Language Models (VLMs)

These models jointly understand images and text.

Actively Used

GPT-4.1 Vision / GPT-4o – Image understanding with natural language reasoning.

LLaVA (newer versions) – Open-source visual QA and chat.

Qwen-VL / Gemini Vision – Production-grade multimodal understanding.

Largely Obsolete / Legacy

Early CLIP-only pipelines – Replaced by integrated multimodal models.

4. Audio / Speech Models

These models process spoken audio.

Actively Used

Whisper (maintained variants) – Speech-to-text across many languages.

Modern TTS stacks – WaveNet-derived and neural TTS systems.

Largely Obsolete / Legacy

DeepSpeech – Superseded by newer speech recognition models.

5. Multimodal Models

These models support multiple modalities but may treat them as separate pipelines.

Actively Used

GPT-4o / GPT-4.1 – Text and image inputs with unified reasoning.

Gemini 3 – Text, image, audio, and long-context support.

Claude 3 – Multimodal reasoning with strong safety guarantees.

Largely Obsolete / Legacy

Early multimodal GPT-4 previews – Replaced by native omni models.

6. Omni Models

Unified models that seamlessly work across modalities.

Actively Used

GPT-4o – Native handling of text, image, and audio.

Gemini Omni – End-to-end multimodal interaction.

Qwen Omni – Open-source omni-style conversational model.

Largely Obsolete / Legacy

None (category is relatively new).

7. Code Models

These models are optimized for programming languages.

Actively Used

GPT-4.1 / GPT-5 Code – Code generation, refactoring, and reasoning.

Code LLaMA – Open-source coding assistant.

DeepSeek Code – Strong code reasoning and generation.

Largely Obsolete / Legacy

Early Codex models – Superseded by newer code-specialized LLMs.

8. Embedding Models

These models convert content into numerical vectors.

Actively Used

text-embedding-3-large – High-quality semantic embeddings.

Instructor – Task-aware embeddings.

Largely Obsolete / Legacy

Older sentence transformers – Used mainly in legacy systems.

9. Reranking Models

These models score and reorder retrieved documents.

Actively Used

Cohere Rerank – Production search relevance.

Cross-encoder MiniLM – Lightweight reranking.

Largely Obsolete / Legacy

Classic BM25-only ranking – Insufficient alone for modern RAG.

10. Reasoning Models

These models focus on structured, multi-step reasoning.

Actively Used

OpenAI o-series – Advanced multi-step reasoning.

Claude 3 Opus – Long-form analytical reasoning.

DeepSeek R1 – Explicit reasoning optimization.

Largely Obsolete / Legacy

None (reasoning specialization is expanding).

11. Tool-Calling / Agentic Models

These models are designed to invoke tools and APIs.

Actively Used

GPT-4.1 / GPT-5 – Native function and tool calling.

Claude 3 – Structured agent workflows.

Largely Obsolete / Legacy

Prompt-only tool chaining – Replaced by native tool APIs.

12. Fine-Tuned / Domain-Specific Models

These models are adapted for specific industries or tasks.

Actively Used

Medical, legal, finance-tuned models – Compliance and domain accuracy.

Largely Obsolete / Legacy

Static rule-based NLP systems – Replaced by fine-tuned LLMs.

13. Generative Image Models

These models generate images from prompts.

Actively Used

DALL·E 3 – High-quality image generation.

Stable Diffusion XL – Open image synthesis.

Midjourney – Creative and artistic generation.

Largely Obsolete / Legacy

Early GAN-based image generators – Lower quality and controllability.

14. Video Models

These models understand or generate video.

Actively Used

Sora – Text-to-video generation.

Runway Gen-2 – Video generation and editing.

Largely Obsolete / Legacy

Rule-based video synthesis – Rarely used today.

15. Hybrid RAG Models

These models are designed to work closely with retrieval systems.

Actively Used

LLMs combined with vector databases – Enterprise knowledge systems.

LangChain / LangGraph RAG – Orchestrated retrieval workflows.

Largely Obsolete / Legacy

Pure long-prompt stuffing – Inefficient and brittle.

See Also

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