An HTML form with a pre-selected checkbox:
The checked attribute is supported in all major browsers.
The checked attribute is a boolean attribute.
When present, it specifies that an <input> element should be pre-selected (checked) when the page loads.
The checked attribute can be used with <input type="checkbox"> and <input type="radio">.
In XHTML, attribute minimization is forbidden, and the checked attribute must be defined as <input checked="checked" />.
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