Decoder. plain-English AI glossary

Foundation model

● Core

A big, general model trained once on broad data, then adapted to countless specific jobs instead of building one from scratch each time.

Think of it like

A liberal-arts graduate you can train up for almost any role, versus hiring a narrow specialist per task.

Example

The same base model powers a coding assistant, a support bot, and a summarizer.

How it actually works

The term captures a shift: instead of training a bespoke model per task, you train one large general model and adapt it — by prompting, retrieval, or fine-tuning. That reuse is why capabilities spread so fast, and why a handful of expensive base models sit under thousands of products.

For product teams

Build on one general model and specialize it — cheaper and faster than bespoke models per feature.

For engineers

A large pretrained model reused across tasks via prompting, RAG, or fine-tuning.

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