Decoder. plain-English AI glossary

Sparse model

▲ Rising

A model that switches on only the parameters it needs per token, so it can be huge but cheap to run.

Think of it like

A big hospital where each patient sees just the right specialists, not every doctor on staff.

Example

A mixture-of-experts model might hold eight times the parameters of a dense one but only light up a fraction per token.

How it actually works

Sparse models — chiefly mixture-of-experts — route each token to a few “expert” subnetworks instead of the whole thing. That decouples total capacity from per-token compute: more knowledge, similar cost. The catch is added complexity in routing, load balancing, and serving.

For product teams

The trick behind models that are “enormous” yet affordable to run — capacity without proportional cost.

For engineers

Conditional computation (e.g. MoE) activating a subset of parameters per token via a router.

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