Models
Large language model (LLM)
A large language model is a neural network trained to predict the next token in a sequence, which turns out to be enough to produce useful text, code and reasoning.
Also written: LLM
Everything an LLM does is next-token prediction. Answering a question, writing code and following instructions are all the same operation applied repeatedly, with each generated token becoming part of the input for the next.
That single mechanism explains most of the behaviour people find surprising: why output length drives latency almost linearly, why asking a model to show its working improves accuracy, and why it will confidently produce a plausible next token even when no correct one exists.
In practice
The commercially relevant fact is that capability and price no longer move together in a simple way. Classification, extraction, routing and formatting are close to saturated on small models, and the price gap between tiers is often more than tenfold. Sending easy traffic to a frontier model is the single most common source of an avoidable bill.
Common questions
Do I need the most capable model?
Usually not. Classification, extraction, routing and formatting are close to saturated on small models, and the price gap between tiers is often more than tenfold. Reserve the frontier tier for open-ended reasoning.
How do I choose between models?
On price, context window and tokenizer availability, which are facts — then on your own evaluation set, which is the only measurement of quality that applies to your data. Leaderboards are not a prediction about your task.
Measure it
- LLM Token CounterReal BPE tokenization, not characters ÷ 4. Shows which counts are exact and which are estimates.
- LLM API Cost CalculatorRequests per month in, dollars out. Input, cached input and output priced separately.
- LLM Model FinderSet a budget and a context requirement, get the shortlist. Sorted by your own input-to-output ratio.