What it is and the problem it solves
ELIZA is an early natural language processing program that simulates conversation. It solves no practical communication problem. It was built to explore human-machine interaction, not to assist, inform, or automate.
How it works
ELIZA matches input text against keywords assigned precedence numbers by its script. It places matching keywords in a keystack, ordered by rank. It then applies a decomposition rule and a reassembly rule tied to the highest-ranked keyword to transform the sentence.
What works
The DOCTOR script reliably reflects user inputs as non-directional questions. Its keyword-ranking and rule-based transformation produce plausible-seeming replies for simple, keyword-rich utterances within narrow linguistic bounds.
What does not
ELIZA does not understand language. It does not infer meaning, retain context across turns, or generalise beyond its scripted rules. It cannot handle ambiguity, contradiction, or syntax outside its decomposition templates.
What it changes
ELIZA changes how people project meaning onto machines. It reveals the ease with which users anthropomorphise shallow interactivity — especially when framed as therapy — exposing a vulnerability in human-machine interaction design.
Is it worth your time
No. ELIZA offers no real understanding, no learning, and no adaptation. It is a static pattern-matching tool with no utility beyond demonstration or historical study.