Performance and cost

A standard test used to score models against each other, useful for shortlisting and unreliable as a promise about your own work.

The wait between sending a request and getting the answer.

Running a trained model to produce an answer, as opposed to training it in the first place.

What it costs to run a model each time it answers, which is why heavy use is metered and the strongest models are rationed.

A cap on how many requests you may send in a given period, which protects the service and shapes how fast an automated job can run.

The ceiling a plan puts on how much you can do in a day, week or month before you are slowed, switched to a weaker model, or stopped.

Paying for what you actually use rather than a flat subscription, which suits uneven demand and makes forecasting harder.

A free tier is a usable product at no cost, with limits such as message caps or slower models; freemium describes the business model built around it, where the free version exists to sell the paid one.

Reusing the work already done on a repeated piece of context, which cuts both cost and wait when the same material is sent often.

Charging by the amount of text going in and coming out rather than per person, which makes long documents cost more than short questions.

A prepaid unit a vendor charges against, worth checking carefully because one credit rarely means the same thing across two products.

Paying a fixed amount per person per month, predictable to budget for and wasteful when only some of those people use it.

Paying for what you actually consume, which rewards light use and can surprise you in a busy month without a cap in place.

The amount of use a plan includes before extra charges begin, the number worth finding before comparing two headline prices.

A contractual promise about availability and response times, with agreed consequences, and the thing to ask for before depending on a tool.

Sending each request to whichever model suits it, keeping the expensive one for the hard cases and something cheaper for the rest.

The address your software sends requests to for a particular model, which is what you are really buying when you buy access.

Running a model on infrastructure someone provides, whether the model maker's, a cloud vendor's or your own.

A single point every AI request passes through, so keys, spending limits, logging and model choice are managed in one place.

How much work a system gets through in a given time, the number that matters for bulk jobs where a single reply's speed does not.

What one completed piece of work costs rather than what one person or one month costs, the unit that makes AI spending comparable to labour.

The reason a long document costs more to ask about than a short one, because everything you send is charged for on the way in.

How many requests a plan lets you run at the same time, usually the first limit a team meets when it moves past piloting.

What you are charged once an included allowance runs out, and the commonest unpleasant surprise on an AI invoice.