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Glossary

Every bit of AI jargon used across this collection, explained simply — no prior knowledge assumed. If a word in one of the sheets tripped you up, it's almost certainly defined here. Skim a section, or jump straight to what you need.

1  The basics
Token
the unit AI works in

The little chunk of text an AI model reads and writes. Roughly ¾ of a word — "tokenization" might be 3 tokens. Everything (price, speed, energy) is counted in tokens.≈ syllables for a machine.

Input vs. output tokens
what goes in / what comes back

Input = the text you send (your question + any context). Output = the text the model writes back. On paid plans, output usually costs several times more than input.

Prompt
your message

Whatever you type or send to the AI — a question, an instruction, a document to summarize. The model responds to the prompt.

Context window
how much it can hold in mind

The maximum amount of text (in tokens) a model can consider at once — your prompt plus its reply plus the conversation so far. Long chats and big attachments fill it up.≈ the model's short-term memory.

LLM
Large Language Model

The big AI model behind chatbots like Claude, ChatGPT, and Gemini. Trained on huge amounts of text to predict and generate language.

SLM
Small Language Model

A smaller, faster, cheaper model. Modern small models match the big flagships of ~18 months ago on most everyday tasks — which is why "right-sizing" saves so much.

Parameters
"8B" = 8 billion

The model's internal adjustable values — a rough proxy for its size and capability. "qwen3:8b" means 8 billion parameters. More isn't always better for a given task.

Flagship model
the top of the line

A provider's most capable (and usually priciest) model — e.g. Claude Opus, GPT-5.5, Gemini Pro. Smaller siblings trade some smarts for speed and cost.

Inference
the model answering

The act of running a trained model to get an answer. Every chat reply is one inference. This is what you pay for and what draws power day-to-day.Seen in: AIBox energy, demand vs. supply

Training
building the model

The one-time, very expensive process of creating a model from data — done once by the provider. After that, the model is used over and over via inference.

Open weights
download & run yourself

Models whose files are published so anyone can download, run, or self-host them (e.g. Meta's Llama, DeepSeek). The opposite of closed, API-only models.Seen in: pricing sheet, AIBox

Tokenizer
the text-into-tokens splitter

The component that chops text into tokens. Different models count differently, so the same sentence can be more or fewer tokens depending on the model.

2  Plans, pricing & money
Consumer plan
the flat monthly fee

A subscription like Claude Pro or ChatGPT Plus (~$20/mo). You pay a fixed price and get an allowance of usage — you never see tokens, just limits.≈ an all-you-can-eat buffet.

API
AY-pee-eye

The developer doorway into a model. Instead of a chat app, software connects directly and is billed per token used.≈ a utility meter.

$/MTok
per million tokens

How API pricing is quoted: dollars per million tokens. E.g. "$5 / MTok input" = $5 for every million tokens you send.

Rate limit
the speed cap

A ceiling on how fast you can send requests (tokens or requests per minute) — not a bill, just a pace limit so the service stays fair and stable.

Prompt caching
reuse, don't re-pay

If you send the same context repeatedly, the provider can cache it and charge up to 90% less on those repeated parts. A big cost saver for apps.

Batch API
cheaper if you can wait

Submit a pile of work to run later (within hours) instead of instantly, for roughly half price. Great for non-urgent jobs.

Right-sizing
the biggest money & energy lever

Choosing the smallest model that still does the job. Using a giant model for a trivial task wastes money and power; matching model to task is the single best optimization.

Cost predictability
fixed vs. variable

Consumer plans are fixed — the bill can't surprise you. API spend is variable — it scales with how much you use, which is ideal for automation.

3  Energy & environment
Watt (W)
a rate of power

How fast something uses energy right now. A 60 W idle box is drawing 60 watts continuously. Like speed (mph), it's an instant reading, not a total.

Wh / kWh
energy = power × time

A watt-hour is one watt for one hour. A kilowatt-hour (kWh) is 1,000 of those — the unit on your electric bill. Power × time = energy.Watts = speed; watt-hours = distance traveled.

TWh
terawatt-hour

One billion kWh — country-scale energy. Used to describe how much electricity all data centers consume (~1,000 TWh/yr globally).

gCO₂e
grams of CO₂-equivalent

A measure of climate impact: grams of carbon dioxide (or its warming equivalent) released. The carbon "cost" of the energy used.

Grid intensity
how clean your power is

How much carbon your local electricity carries, in gCO₂ per kWh. Solar/nuclear ≈ low; coal/gas ≈ high. The same query is "greener" on a cleaner grid.

PUE
data-center overhead

Power Usage Effectiveness — extra energy a data center spends on cooling and overhead beyond the computers themselves. PUE 1.09 = 9% overhead (very efficient).

Embodied carbon
the "making it" footprint

Emissions from manufacturing the hardware, before it's ever switched on. Reusing old hardware makes this ~0 — a real green advantage.

Idle power
the always-on baseline

What a device draws while doing nothing but staying on. For a lightly-used always-on box, idle dominates the whole footprint.Seen in: AIBox energy

Full vs. marginal attribution
two honest ways to count

Full: charge each query its share of the 24/7 idle power (treats the box as a dedicated appliance). Marginal: count only the extra power used while actually working (treats the box as "on anyway"). The per-query number can swing wildly between them.

Operational water
cooling water

Water some data centers evaporate to cool their chips, measured in mL per query. An air-cooled home box uses ~0.

4  Under the hood & why it's getting cheaper
GPU
Graphics Processing Unit

The specialized chip that runs AI fast. Originally built for video-game graphics, now the workhorse of AI inference and training.

Quantization
shrink the numbers

Storing a model's values at lower precision so it runs faster and cheaper, with little quality loss. A common efficiency trick.

Distillation
small model learns from big

Training a compact model to imitate a large one — capturing most of the smarts at a fraction of the cost to run.

Mixture-of-Experts (MoE)
only part runs each time

A model design where only the relevant slice of the network activates per query, so a "big" model runs at a small model's cost.

Speculative decoding
a speed trick

A small model drafts several tokens ahead and the big model checks them in bulk — producing answers faster for the same quality.

LLMflation
prices falling fast

The observed trend that, for equal quality, AI inference gets roughly 10× cheaper every year — faster than computing got cheap in the PC era.Seen in: the optimistic case

Jevons paradox
efficiency → more use

When something gets cheaper/more efficient, people use much more of it — so total consumption can rise even as each use gets greener. Why demand keeps climbing.

5  Reading the charts
Log scale
each gridline ×10 (or ×1,000)

A way to plot wildly different sizes on one chart: each step multiplies instead of adds. Lets "1 million" and "1 quadrillion" share a graph. Watch for it — bars aren't to linear scale.Seen in: who burns the tokens

Growth multiple (×N)
how many times bigger

"×330" means 330 times the starting value — a measure of growth rate, not absolute size. Two ×-figures compare how fast things grew, not how big they are.

Estimated vs. measured
labeled throughout

Measured = read from real instruments or logs. Estimated = a reasonable default where no measurement exists. The sheets mark which is which so you know how much to trust a number.Seen in: AIBox energy

MTok / Q / T
big-number shorthand

M = million, B = billion, T = trillion, Q = quadrillion (1,000 trillion). "3.2 Q tokens/month" = 3,200 trillion tokens a month.

About — This guide covers the vocabulary used across the five sheets in the collection. Definitions favor clarity over precision — for exact figures, methods, and sources, see the individual sheets. Missing a term? It's a living page; it can grow.