---
title: Comments
---

The way Sass comments work differs substantially between SCSS and the indented
syntax. Both syntaxes support two types of comments: comments defined using `/*`
that are (usually) compiled to CSS, and comments defined using `//` that are
not.

## In SCSS

Comments in SCSS work similarly to comments in other languages like JavaScript.
**Single-line comments** start with `//`, and go until the end of the line.
Nothing in a single-line comment is emitted as CSS; as far as Sass is concerned,
they may as well not exist. They're also called **silent comments**, because
they don't produce any CSS.

**Multi-line comments** start with `/*` and end at the next `*/`. If a
multi-line comment is written somewhere that a [statement][] is allowed, it's
compiled to a CSS comment. They're also called **loud comment**, by contrast
with silent comments. A multi-line comment that's compiled to CSS may contain
[interpolation][], which will be evaluated before the comment is compiled.

By default, multi-line comments be stripped from the compiled CSS in [compressed
mode][]. If a comment begins with `/*!`, though, it will always be included in
the CSS output.

[statement]: structure#statements
[interpolation]: ../interpolation
[compressed mode]: ../cli/dart-sass#style

<% example(syntax: :scss) do %>
  // This comment won't be included in the CSS.

  /* But this comment will, except in compressed mode. */

  /* It can also contain interpolation:
   * 1 + 1 = #{1 + 1} */

  /*! This comment will be included even in compressed mode. */

  p /* Multi-line comments can be written anywhere
     * whitespace is allowed. */ .sans {
    font: Helvetica, // So can single-line commments.
          sans-serif;
  }
<% end %>

## In Sass

Comments in the indented syntax work a little differently: they're
indentation-based, just like the rest of the syntax. Like SCSS, silent comments
written with `//` are never emitted as CSS, but unlike SCSS everything indented
beneath the opening `//` is also commented out.

Indented syntax comments that start with `/*` work with indentation the same
way, except that they are compiled to CSS. Because the extend of the comment is
based on indentation, the closing `*/` is optional. Also like SCSS, `/*`
comments can contain [interpolation][] and can start with `/*!` to avoid being
stripped in compressed mode.

Comments can also be used within [expressions][] in the indented syntax. In this
case, they have exactly the same syntax as they do in SCSS.

[expressions]: structure#expressions

<% example(syntax: :sass) do %>
  // This comment won't be included in the CSS.
     This is also commented out.

  /* But this comment will, except in compressed mode.

  /* It can also contain interpolation:
     1 + 1 = #{1 + 1}

  /*! This comment will be included even in compressed mode.

  p .sans
    font: Helvetica, /* Inline comments must be closed. */ sans-serif
<% end %>

## Documentation Comments

When writing style libraries using Sass, you can use comments to document the
[mixins][], [functions][], [variables][], and [placeholder selectors][] that
your library provides, as well as the library itself. These are comments are
read by the [SassDoc][] tool, which uses them to generate beautiful
documentation. Check out [the Susy grid engine][susy]'s documentation to see it
in action!

[mixins]: ../at-rules/mixin
[functions]: ../at-rules/function
[variables]: ../variables
[placeholder selectors]: ../style-rules/placeholder-selectors
[SassDoc]: http://sassdoc.com
[susy]: http://oddbird.net/susy/docs/index.html

Documentation comments are silent comments, written with three slashes (`///`)
directly above the thing you're documenting. SassDoc parses text in the comments
as [Markdown][], and supports many useful [annotations][] to describe it in
detail.

[Markdown]: https://www.markdownguide.org/getting-started
[annotations]: http://sassdoc.com/annotations/

<% example do %>
  /// Computes an exponent.
  ///
  /// @param {number} $base
  ///   The number to multiply by itself.
  /// @param {integer (unitless)} $exponent
  ///   The number of `$base`s to multiply together.
  /// @return {number} `$base` to the power of `$exponent`.
  @function pow($base, $exponent) {
    $result: 1;
    @for $_ from 1 through $exponent {
      $result: $result * $base;
    }
    @return $result;
  }
  ===
  /// Computes an exponent.
  ///
  /// @param {number} $base
  ///   The number to multiply by itself.
  /// @param {integer (unitless)} $exponent
  ///   The number of `$base`s to multiply together.
  /// @return {number} `$base` to the power of `$exponent`.
  @function pow($base, $exponent)
    $result: 1
    @for $_ from 1 through $exponent
      $result: $result * $base

    @return $result
<% end %>