The async attribute specifies that the script will be executed asynchronously as soon as it is available. And It is a boolean attribute. The async attribute is only for external scripts usage and it can be used only if the src attribute is present. Tag Support You can use the async attribute with <script> tag.
The alt attribute provides alternative information for an image if it can not be viewed by a viewer for some reason (because of a poor link, a mistake in the src attribute, or using a screen reader by the user). The <img> tag requires the alt attribute. In <input> elements, the alt attribute can only
The action attribute indicates where to send the form data on submitting the form by the user. (e.g. a PHP script that handles the form data). You can use action attribute on form tag. Example Browser Support
Global accesskey attribute provides a hint for the current element to generate a keyboard shortcut. The value of the attribute must be a single printable character (including accented and other characters that the keyboard can generate) In separate browsers, the manner to access the shortcut key varies. As this is the part of HTML global attributes you can use this on any HTML tag. However, the shortcut can be put to another key mix in most browsers.
The accept-charset attribute indicates the encoding characters to be used for submitting the form. The default value of accept-charset attribute is UNKNOWN (there is no default value of this attribute), and it’s mean that encoding equals the encoding of the document containing the <form> element. You can use accept-charset attribute with the form tag. Example Syntax Attribute
The accept attribute Specify which type of file user can choose from the input picker. This attribute is valid for only input type=”file” Example Note: You can use accept attribute only for <input type=”file”>. Tip: Do not use this attribute as a validation tool. File uploads should be validated on the server for better validation. Syntax Separate the values with a comma to indicate more than one value (e.g. <input accept=” image/*, video/*, audio/*,” />. Attribute Values