> For the complete documentation index, see [llms.txt](https://help.protecto.ai/getting-started/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://help.protecto.ai/getting-started/protecto-overview/introduction/protecto-vault/what-is-a-token.md).

# What is a token?

A token is like a special key that represents something valuable but doesn't directly show what that valuable thing is. It's used to protect important information, like a secret code, without revealing the actual code itself.

Here are some options to define a token:

1. **`Text-Based Tokens:`**
   * **`Random Text`:** Generate random alphanumeric characters as tokens, ensuring uniqueness and unpredictability.
2. **`Alphanumeric Tokens:`**
   * **`Random Alphanumeric:`** Combine random letters and numbers to create tokens that are both secure and user-friendly.
3. **`Format-Preserved Tokens:`**
   * **`Preserve Certain Characters`:** Maintain specific characters, such as separators or hyphens, while tokenizing the rest of the data. This helps users recognize the format of the original data.
4. **`Custom Tokens:`**
   * **`User-Defined Patterns`:** Allow users to define their own token patterns or formats based on their needs and preferences.
5. **`Length of Tokens`:**
   * **`Fixed-Length Tokens`:** Specify a fixed length for tokens, ensuring consistency and compatibility with data structures.
   * **`Variable-Length Tokens`:** Allow tokens to vary in length based on the length of the original data.