What Is a Token in AI? An Explainer

A token in AI is the smallest unit of text that models use to interpret language, which can be a whole word, part of a word, a character, or even a phrase, and is central to how AI processes and generates text. Tokenization involves breaking down text into these units before processing, allowing models to recognize patterns and understand novel words by combining known segments, optimizing for computational efficiency. This process differentiates tokens from words and characters by managing vocabulary size and memory constraints, influencing factors like context windows, cost, response time, and output quality. For developers and data architects, understanding tokens is crucial for designing efficient prompts and structuring data for retrieval, which directly impacts performance, latency, and infrastructure needs in AI applications. Token limits define the context window of an AI model, affecting how much information it can remember, and these constraints are essential to managing computational costs and efficiency.