AI chat glossary
Plain-language definitions of the terms used across FanChat and the AI character chat space.
BYOA (Bring Your Own API key)
BYOA is a pricing model where the platform is free and the user supplies their own LLM provider API key. Inference is billed by the provider (OpenAI, Anthropic, Google, etc.) directly to the user at cost, with no platform markup and no subscription. FanChat is a BYOA platform.
BYOK (Bring Your Own Key)
BYOK is a synonym of BYOA used interchangeably in the AI tooling space: the user brings their own API key instead of paying the platform for hosted inference.
AI character
An AI character is a reusable conversation template: a system prompt defining personality, example dialogues defining response style, an optional knowledge base, mood and voice settings. The character itself runs no inference; the user who chats with it activates it with their own model and tokens.
System prompt
A system prompt is the hidden instruction sent to the LLM before the conversation, defining who the character is, how it speaks, and what it must not do. On FanChat it is generated by the character builder and can be edited manually (up to 8000 characters).
Example dialogues
Example dialogues are 6-10 sample exchanges stored with a character that teach the model its unique response style: tone, length, quirks, vocabulary. They matter more than the description for how a character actually sounds.
Function calling (tools)
Function calling lets an LLM invoke external tools mid-conversation: web search, URL reading, a calculator, code execution, image generation, or domain tools like flight search. The model decides when to call a tool and incorporates the result into its reply.
Platform LLM
On a BYOA platform, the platform LLM is the model the platform itself pays for to power internal features (such as guiding character creation or generating descriptions), as opposed to the chat LLM that runs user conversations on the user’s own key.
Neural TTS
Neural text-to-speech synthesizes natural-sounding speech from text using neural networks. FanChat offers 27 neural voices across 13 languages so any character message can be read aloud, with voices filtered by the character’s language.
See it in practice: FAQ.