Chatbot
A program you talk to by typing or speaking, as if it were a person.
A chatbot is a program designed to hold a conversation. You write or say something, and it answers in words. The idea is old: in 1966 Joseph Weizenbaum at MIT built ELIZA, which imitated a therapist by turning your sentences back into questions. Some users became emotionally attached to it, even knowing it was a simple trick.
For decades, most chatbots were scripted. The bank or airline bot on a website follows a decision tree written by people: it looks for keywords and offers fixed menus ('Type 1 for a refund'). That is predictable and cheap, but it breaks the moment you ask something nobody anticipated.
Modern chatbots like ChatGPT, Claude or Gemini are built on large language models, so they generate each reply on the spot instead of choosing from a script. They understand messy questions and answer naturally, and companies can connect them to their own documents and systems. The trade-off is control: a generated answer can be wrong. In 2024 a Canadian tribunal ordered Air Canada to honor a refund policy its website chatbot had invented, which made clear that a company is responsible for what its bot says.
Keep in mind
- Old chatbots follow scripts; modern ones generate replies with an LLM.
- ELIZA, from 1966, is usually called the first chatbot.
- Generated replies sound natural but can be wrong.
- Companies are responsible for what their chatbots tell customers.
