Explain like I'm five · AI

What are Open Weights?

Open-weight models, told as a story about a parrot whose every number is published, so anyone can bring it home to their own perch.

there are two ways to use a parrottheir counterask at the counterthe borrowed parrotpay beans every time you askbring it to our perchour own parrotwe set up the perch ourselvesborrow it, or bring it home?

There are two ways to use a parrot: ask through their counter, or bring it home to our perch.Ask at the counter and the parrot stays at their house; you pay beans every time. Bring it home and the parrot lives with you.

borrowed-parrot worriesBILLbeans × ten thousand= a lot of moneybeans every timesecretsecret beans leave for their houseown-parrot worriesthe perch (GPU) — priceyTO DOfeedingfixingwatchingbuy the perch, and someone has to care for iteither way has worries — the question is what you want to protect

Either way has worries: borrowing means bean bills and secret beans; bringing home means the perch and the caring.A borrowed parrot costs beans every time, and your secret beans go to their house. Your own parrot needs a pricey perch (GPU) and someone to care for it every day.

WEIGHTS0.31 -0.72 1.052.14 0.08 -0.55… billions of themweights = every number in its headOPEN!LlamaMistralQwenanyone can put it on their own perchopen weights: a parrot whose every number is published, so anyone can put it on their own perch

Open weights: a parrot whose every number in its head is published, so anyone can put it on their own perch.A parrot has billions of numbers (weights) in its head. Publish them all and anyone can download the bird and put it on their own perch — Llama, Mistral, Qwen are such birds. The very smartest parrots are usually met only at the counter.

Data can't leave? Own itkeep secret beans home
The smartest are usually borrowedthey live at the counter
Drill and coarse-count freely at homeour bird, our rules
Read the license scrollit may not be free
BORROWED vs OUR OWNborrowed (counter)our own (perch)costpay per beanpay for the perch up frontfreshnessthe newest parrotsarrives a bit laterwhere data goesto their housestays homefreedom to tweakonly what they allowdrill and coarse-count freelyupkeepalmost nonewe do the caringno single right answer — pick by your data, money and people

Borrowed and own parrots differ in cost, freshness, where data goes, tweaking, and upkeep.Your own parrot can be drilled or made to count beans coarsely as you like. In return, its cost and speed depend on your perch.

free?priceyperch, powerand a keeperweights are free, the perch is notopen source?OPENweights ✓?which books it read: secretweights open, book list closedconditions?LICENSEto use for business…big firms ask firstshow the nameread the scroll firstopen is neither free nor open source — read the scroll

Open is neither free nor open source. The numbers are public, the book list isn't, and business use has conditions.The perch and the caring cost money — compare it with the bean bill. If you brought it home to keep secret beans safe, the daily caring is yours too.

In one breath

Open weights = a parrot whose numbers (weights) are all published, so anyone can put it on their own perch. Secret beans stay home and tweaking is free, but the perch and the caring are yours. Open is neither free nor open source — read the scroll.

A model whose trained parameters (weights) are published so anyone can download it and run inference, fine-tune, or quantize it on their own servers (Llama, Mistral, Qwen, etc.). API models run on the provider's servers, bill per token, and see your data. Unlike true open source, training data and code are usually withheld, and licenses vary on commercial use, user thresholds and attribution. Self-hosting brings GPU cost and operations (LLMOps) with it.

When grown-ups say it

Open weights
The parrot with its numbers published. Anyone can download it and put it on their own perch. Llama, Mistral, Qwen.
Weights
The numbers in the parrot's head. Billions of numbers, set while reading the books. They are the parrot.
API model
The borrowed parrot at the counter. Lives at their house; you pay beans per question. → the bean bill
Self-hosting
Putting the parrot on our own perch. Buy the perch (GPU) and care for it daily. → caring for the parrot
License
The conditions on the scroll. Whether business use is allowed, whether big firms need permission, whether to credit the name — differs per bird.
Open weights vs open source
Numbers open vs books and recipe open too. Open weights publish only the numbers. Which books it read and how it was taught usually stay secret.
Inference server
What makes it answer on our perch. We set its cost and speed. → what answering costs and takes
Quantization
Counting beans coarsely. Possible because it is your bird — it fits a smaller perch. → coarse counting
Next story
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