AI reference
Clear AI definitions and model data you can check.
A glossary written for practitioners, research summaries, and language models compared on price, limits and capabilities, with a source and a date next to every number.
Glossary
266 terms · A–Z
Definitions first, then how it works, worked examples, formulas and code.
LLM API pricing
62 models · 5 vendors
Per-token prices from each vendor's own page, with cache, batch and long-context rates.
Models
7 model cards · 6 comparisons
Context windows, limits and capabilities, with the source behind each value.
Tools
Token counter · cost calculator
Count the tokens in your prompt, then see what a month of traffic costs on every model.
LLM changelog
20 changes · last Sep 15, 2026
Model launches, price changes and retirements, each linked to the vendor's notice.
News and research
177 articles
Pricing news, research summaries and applied machine learning explainers.
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Recently updated in the glossary
Latest articles
Vector Databases: How They Work and How to Choose One
A vector database stores embeddings, the numeric vectors that represent the meaning of text, images or audio, and finds the ones closest to a query vector. It is the…
What Is RAG? Retrieval-Augmented Generation Explained With a Working Example
Retrieval-augmented generation (RAG) is a way to make a large language model answer from information it was never trained on. Before the model responds, a search step…
Claude Sonnet 5 Keeps Its $2 / $10 Price: Anthropic Cancels the Planned Increase
Anthropic launched Claude Sonnet 5 on June 30, 2026, at an introductory price of $2 per million input tokens and $10 per million output tokens, with a scheduled increase…
DeepSeek V4.1 Flash Arrives With Lower Prices, and V4 Pro Gets a Reprieve
DeepSeek released DeepSeek-V4.1-Flash on September 10, 2026, and changed its API prices the same day at 04:00 UTC. The announcement also said the larger V4 Pro would be…
Gemini 3.8 Flash Launch Pricing Ends December 31: API Price Doubles in 2027
Google made Gemini 3.8 Flash generally available in the Gemini API on September 2, 2026. The release notes call it Google's most intelligent Flash model, aimed at…
GPT-5.5 Leaves ChatGPT and Codex on October 14, but Stays in the OpenAI API
OpenAI will remove GPT-5.5 from ChatGPT, ChatGPT Work and Codex on October 14, 2026, across all plans. The company announced the change from its @ChatGPT account on…