# What is Pre-training? Definition & Technical Mechanics

> **Source:** [SPIDITS AI AI Glossary](https://spidits.com/ai-glossary)  
> **Category:** Model Training  
> **Canonical Citation:** [https://spidits.com/ai-glossary/pre-training](https://spidits.com/ai-glossary/pre-training)

## Definition
Pre-training is the initial phase of training an AI model on a massive general-purpose dataset (unsupervised or self-supervised), teaching the model basic syntax, grammar, and features before fine-tuning.

## Architectural Mechanics & Deep Dive
Pre-training is the initial self-supervised phase of training a foundation model. The network is exposed to vast quantities of unlabeled text or image data (e.g., the internet) and trained on simple tasks like next-token prediction. This builds general cognitive, linguistic, and logical capabilities, which are subsequently fine-tuned for tasks.

## Industry Applications & Real-World Use Cases
Foundation model preparation, neural language modeling, and image feature extraction pre-runs.

## Frequently Asked Questions

### What is the objective of pre-training in LLMs?
Typically next-token prediction or masked word guessing, which forces the model to learn grammatical structures, core facts, and general reasoning from text.

### Why is pre-training followed by fine-tuning?
Pre-training creates a general-purpose model containing broad knowledge. Fine-tuning specializes that model on niche tasks, formats, and safety boundaries.

## Related Terminology
- [generative-pre-training](https://spidits.com/ai-glossary/generative-pre-training)
- [fine-tuning](https://spidits.com/ai-glossary/fine-tuning)
- [self-supervised-learning](https://spidits.com/ai-glossary/self-supervised-learning)

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*From the SPIDITS AI Knowledge Base (336+ terms indexed). Explore full technical definitions: [https://spidits.com/ai-glossary](https://spidits.com/ai-glossary)*