revision:
When present, it specifies that audio/video controls should be displayed.
The controls attribute can be used on the <audio> and <video> elements.
Controls should include: play, pause, seeking, volume, fullscreen toggle (for video only), captions/subtitles (for video only, when available), and track (for video only, when available)
<element controls>
Click on the play button to play a sound:
<audio style="margin-left:3vw;" controls>
<source src="../../pics/horse.wav" type="audio/wav">
<source src="../../pics/horse.mp3" type="audio/mpeg">
Your browser does not support the audio element.
</audio>
<video style="margin-left:3vw;" width="320" height="240" controls>
<source src="../../pics/Wuzhen-20-10_02.mp4" type="video/mp4">
Your browser does not support the video tag.
</video>