### What Are Evals?
Evals (short for _evaluations_) are structured tests that measure how well an AI model performs on specific tasks. They give a consistent way to compare models, track improvements, and decide which model is best suited for a job.
Instead of just asking “does the model seem smart,” evals define measurable standards. Example:
- Accuracy on math problems
- Precision in medical diagnosis
- Relevance of search results
- Tone in customer support replies
### Why They Matter
- **Model choice**: There are dozens of AI models, each with different strengths. Evals help you pick the one that performs best for _your_ use case.
- **Quality control**: Evals act like continuous report cards, spotting when a model drifts, degrades, or produces errors.
- **Customization**: Startups can design evals tailored to their domain (e.g., legal, healthcare, finance) and use them to tune models.
- **Switching advantage**: With good evals, a company can swap in the newest, strongest model quickly and keep its edge.
### Example
Imagine you’re building an AI for financial analysis. Off-the-shelf, one model might be better at reasoning with numbers, another at explaining in plain English. A set of evals—say, “Can it summarize a 10-K filing?” or “Does it calculate ratios correctly?”—will show which model is better for your customers.
### The Bigger Picture
Evals are becoming the **moat** for AI companies. Anyone can rent compute or plug into an API, but owning a library of well-designed evals means you uniquely know what “good” looks like in your domain. That knowledge compounds over time.