In SVG, you can specify that any other graphics object or <g> element can be used as an alpha mask for compositing the current object into the background. A mask is defined with the <mask> element. A mask is used/referenced using the mask property.
Usage context
| Categories | Container element | 
|---|---|
| Permitted content | Any number of the following elements, in any order: Animation elements Descriptive elements Shape elements Structural elements Gradient elements <a>,<altGlyphDef>,<clipPath>,<color-profile>,<cursor>,<filter>,<font>,<font-face>,<foreignObject>,<image>,<marker>,<mask>,<pattern>,<script>,<style>,<switch>,<text>,<view> | 
Attributes
Global attributes
- Conditional processing attributes »
- Core attributes »
- Presentation attributes »
- class
- style
- externalResourcesRequired
Specific attributes
DOM Interface
This element implements the SVGMaskElement interface.
Example
SVG
<?xml version="1.0"?>
<svg width="200" height="80" viewBox="0 0 200 80" version="1.1"
    xmlns="http://www.w3.org/2000/svg" 
    xmlns:xlink="http://www.w3.org/1999/xlink">
  <defs>
    <mask id="myMask" maskUnits="userSpaceOnUse"
        x="0" y="0" width="200" height="80">
      <rect x="0" y="0" width="100" height="80" fill="white"/>
    </mask>
    <text id="Text" x="100" y="48" font-size="26" font-weight="bold"
        text-anchor="middle">
      Black & White
    </text>
  </defs>
  <!-- Draw black rectangle in the background -->
  <rect x="100" y="10" width="95" height="60" />
  <!-- Draw the text string twice. First, the white text without mask.
       Second, the black text with the mask applied-->
  <use xlink:href="#Text" fill="white"/>
  <use xlink:href="#Text" fill="black" mask="url(#myMask)"/>
</svg>
Result
Specifications
| Specification | Status | Comment | 
|---|---|---|
| CSS Masking Level 1 The definition of '<mask>' in that specification. | Candidate Recommendation | |
| Scalable Vector Graphics (SVG) 1.1 (Second Edition) The definition of '<mask>' in that specification. | Recommendation | Initial definition | 
Browser compatibility
| Feature | Chrome | Edge | Firefox (Gecko) | Internet Explorer | Opera | Safari | 
|---|---|---|---|---|---|---|
| Basic support | (Yes) | (Yes) | (Yes) | (Yes) | (Yes) | ? | 
| Feature | Android | Edge | Firefox Mobile (Gecko) | IE Phone | Opera Mobile | Safari Mobile | 
|---|---|---|---|---|---|---|
| Basic support | ? | (Yes) | ? | ? | ? | ? |