AI

Foundation Models

A practical guide to understanding what foundation models are and why they matter for AI product development.

What foundation models are, how they differ from traditional software, and what product and design teams need to know when building on top of them.

22 May 20264 min read

What it is

A foundation is a large AI model trained on a broad range of that can be adapted and applied to a wide variety of tasks.

Rather than training a specialised for each specific use case, a foundation model provides a general-purpose base that can be prompted, fine-tuned, or connected to external tools to handle many different applications.

GPT-4, Claude, Gemini, and Llama are examples of foundation . Most AI products you interact with are built on top of one of these, rather than training an entirely new model from scratch.

Foundation represent a fundamental shift in how software is built. Rather than writing explicit rules for every , you are building on a that has learned from an enormous range of human-generated content.

That power comes with limitations — including inherited , hallucination risk, and that can be difficult to predict or fully control.

When to use it

Understand when building on a foundation is the right approach.

It is most relevant when:

You are building AI-powered features and evaluating which model to build on
You are assessing the capabilities and limitations of an existing AI product
You need to understand the difference between the model and the product built on top of it
You are making decisions about model selection, switching, or evaluation

Key takeaway

Understanding foundation models helps you understand both the power and the inherited limitations of the AI features you build or use.

How it works

Understand the basic mechanism. Foundation are trained on enormous — often hundreds of billions of words of text — using a called self-supervised learning. This produces a model with broad general capabilities.

From there, the can be used directly through an API, fine-tuned on specific to improve on a target task, or extended with tools and retrieval systems to handle specialised use cases.

The provider — OpenAI, Anthropic, Google, and others — is responsible for training, maintaining, and updating the foundation model. Product teams on top of it, often without full visibility into exactly how it was trained or what it contains.

What this means for designers and product teams. Building on a foundation means inheriting both its strengths and its limitations. The model's knowledge cutoff, , and failure modes become your product's knowledge cutoff, biases, and failure modes unless you actively design around them.

providers update foundation models over time, which can change . A product that works reliably today may behave differently after a model update — making monitoring and evaluation an ongoing responsibility.

What to look for

Focus on:

Model capabilities — what the model does well and where it struggles
Knowledge boundaries — what the model knows and what lies beyond its training cutoff
Inherited limitations — what biases or failure modes are present in the model
Provider reliability — the track record and roadmap of the model provider
Update policies — how model updates are communicated and managed

Where it goes wrong

Most issues come from: Treating a foundation as a black box and hoping for the best is not a .

No ongoing evaluation after initial deployment
Assuming model updates will only make things better
No testing for inherited bias or hallucination risk
Choosing a model based on benchmark performance rather than real-world task performance
No contingency plan if the model provider changes access, pricing, or terms

What you get from it

Understanding foundation gives you:

Clearer expectations about what AI features can and cannot do reliably
A better framework for model selection and evaluation
Awareness of the risks that come with building on models you do not fully control
More informed conversations with engineers and leadership about AI product strategy

Key takeaway

Foundation models are powerful but not neutral. Knowing what you are building on — and what it comes with — is the foundation of responsible AI product design.

FAQ

Common questions

A few practical answers to the questions that usually come up around this method.

What is a foundation model?

A foundation is a large AI model trained on broad that can be adapted to a wide range of tasks. Rather than training a new model for each use case, most products are built on top of an existing foundation model from providers like OpenAI, Anthropic, or Google.

How is a foundation model different from the AI product built on top of it?

The foundation is the underlying — the trained that understands and generates language. The product built on top of it adds structure, tools, prompts, and design to make that capability useful for a specific purpose. The model provides the intelligence; the product provides the context and application.

Can I switch foundation models?

Technically yes, but it is not trivial. Different have different , , and failure modes. Switching models requires re-evaluation of your prompts, system design, and quality standards. It is worth planning for the possibility from the start rather than building in a way that makes switching difficult.

What happens when a foundation model is updated?

The provider a new with different performance characteristics. This can improve outputs in some areas while changing behaviour in others. Monitoring your AI feature's performance after model updates and testing before switching to a new version are both essential.

Are smaller or open-source models a viable alternative?

For some use cases, yes. Smaller can be faster, cheaper, and easier to deploy privately. Open-source models offer more control and transparency. The trade-off is typically — larger proprietary models tend to outperform smaller alternatives on complex tasks, though that gap is narrowing.

Quick take

Most AI products are not building models — they are building on top of foundation models. Understanding what that means changes how you design, evaluate, and manage risk.

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