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How to write comments in YAML

Tarun Telang


YAML is a popular data serialization format that is commonly used in many different programming languages. In order to write effective YAML code, it is important to understand how to use comments effectively. This involves understanding the syntax for adding comments as well as knowing when and where to use them.


Comments in YAML are denoted by using the hash symbol # at the beginning of the comment line. For example, the following code snippet shows how to add a single-line comment:

# This is a single-line comment
Single-line comment in YAML

A comment can begin anywhere in the line. See the example below to understand how this can be done:

key: "value" # mapping
   # A list of two items
  - "item 1" # first value
  - "item 2" # second value
Inline comments in YAML

The hash # marks the beginning of a comment and any text until the end of the line is considered part of the comment. Hence, it is completely ignored by YAML parsers.

YAML does not support block or multi-line comments. In order to create a multi-line comment, we need to suffix each line with a #.

# This is a multi-line 
# comment in YAML. There is 
# no alternate way of creating
# block comments.
Multi-line comment in YAML

When and where to use comments

In general, it's a good idea to use comments sparingly and only when absolutely necessary. This is because adding too many comments can actually make the code more difficult to read and understand. In most cases, it's best to add comments where the code is complex or convoluted, or where there is a need to provide additional instructions on how to use certain features.

Additionally, we should avoid using comments to duplicate information that is already provided in the documentation or existing comments.


The use of effective comments in YAML can help make our code more readable and easier to understand for other programmers. To become skilled in YAML, it's important to understand the syntax for adding comments as well as when and where to use them.

By following these basic tips mentioned above, we can write code that is both clean and well-documented.



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