Token
1. What Is It?
One-sentence definition
A Token is the smallest text-processing unit used by an AI model, and it is also the basic unit used for pricing. It is not exactly the same as a word or a character. It is closer to a semantic fragment.
2. How It Works
The model cannot read plain text directly. It first converts text into token IDs through tokenization.
3. Tokens and Pricing
- Chinese often consumes more tokens
- English is often more token-efficient
- both input and output are usually billed
4. Why Long Conversations Become Expensive
Because multi-turn systems often resend earlier history along with the new message, token consumption grows much faster than users expect.
5. Intuitive Analogies
- tokens are like puzzle pieces
- tokens are like a taxi meter
- the context window is like a fuel tank
6. Practical Ways to Save Tokens
| Method | Example |
|---|---|
| Ask more directly | Remove unnecessary filler |
| Limit answer length | "Answer in under 100 words" |
| Start a new conversation when needed | Avoid endlessly growing history |
| Use summaries | Compress earlier turns |
| Choose the right model | Cheap model for simple tasks |
7. What You Need to Remember
- tokens are the unit of model text processing and billing
- both cost and context length depend on tokens
- a large amount of AI engineering is really about using limited tokens more efficiently
8. Recommended Reading
- Product manager article: https://www.woshipm.com/ai/6184349.html
- CSDN article: https://blog.csdn.net/qq_27471405/article/details/140486945
- Alibaba Cloud explainer: https://developer.aliyun.com/article/1529782
- OpenAI tokenizer: https://platform.openai.com/tokenizer