why name = in meta tag code example

Example 1: meta tags

<head>
  <meta charset="UTF-8">
  <meta name="description" content="Free Web tutorials">
  <meta name="keywords" content="HTML, CSS, JavaScript">
  <meta name="author" content="John Doe">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
</head>

Example 2: all meta name attribute

<meta name="og:title" content="The Rock"/>
<meta name="og:type" content="movie"/>
<meta name="og:url" content="http://www.imdb.com/title/tt0117500/"/>
<meta name="og:image" content="http://ia.media-imdb.com/rock.jpg"/>
<meta name="og:site_name" content="IMDb"/>
<meta name="og:description" content="A group of U.S. Marines, under command of..."/>

<meta name="fb:page_id" content="43929265776" />

<meta name="og:email" content="[email protected]"/>
<meta name="og:phone_number" content="650-123-4567"/>
<meta name="og:fax_number" content="+1-415-123-4567"/>

<meta name="og:latitude" content="37.416343"/>
<meta name="og:longitude" content="-122.153013"/>
<meta name="og:street-address" content="1601 S California Ave"/>
<meta name="og:locality" content="Palo Alto"/>
<meta name="og:region" content="CA"/>
<meta name="og:postal-code" content="94304"/>
<meta name="og:country-name" content="USA"/>

<meta property="og:type" content="game.achievement"/>
<meta property="og:points" content="POINTS_FOR_ACHIEVEMENT"/>

<meta property="og:video" content="http://example.com/awesome.swf" />
<meta property="og:video:height" content="640" />
<meta property="og:video:width" content="385" />
<meta property="og:video:type" content="application/x-shockwave-flash" />
<meta property="og:video" content="http://example.com/html5.mp4" />
<meta property="og:video:type" content="video/mp4" />
<meta property="og:video" content="http://example.com/fallback.vid" />
<meta property="og:video:type" content="text/html" />

<meta property="og:audio" content="http://example.com/amazing.mp3" />
<meta property="og:audio:title" content="Amazing Song" />
<meta property="og:audio:artist" content="Amazing Band" />
<meta property="og:audio:album" content="Amazing Album" />
<meta property="og:audio:type" content="application/mp3" />

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