What is structured data or schema

Structured markup tells Google or other Search Engines about the content type or format such as News, Article, Recipe, Music, Movie, Video, etc.

There are two ways to achieve the structured markup for your site. One with the HTML Tags and attributes (Microdata) and the other with script format (JSON-LD). But nowadays, the JSON-LD format is being used widely.

Here are the various schema markup examples based on content type. 

https://developers.google.com/search/docs/appearance/structured-data/search-gallery

For articles it looks like this:

JSON-LD in <head>Microdata <body>
 <script type=”application/ld+json”>    {
      “@context”: “https://schema.org/”,
      “@type”: “Recipe”,
      “name”: “Party Coffee Cake”,
      “author”: {
        “@type”: “Person”,
        “name”: “Mary Stone”
      },
      “datePublished”: “2018-03-10”,
      “description”: “This coffee cake is awesome and perfect for parties.”,
      “prepTime”: “PT20M”
    }
    </script>
 <div itemscope itemtype=”https://schema.org/NewsArticle”>      <div itemprop=”headline”>Title of News Article</div>
      <meta itemprop=”image” content=”https://example.com/photos/1×1/photo.jpg” />
      <meta itemprop=”image” content=”https://example.com/photos/4×3/photo.jpg” />
      <img itemprop=”image” src=”https://example.com/photos/16×9/photo.jpg” />
      <div>
        <span itemprop=”datePublished” content=”2015-02-05T08:00:00+08:00″>
          February 5, 2015 at 8:00am
        </span>
        (last modified
        <span itemprop=”dateModified” content=”2015-02-05T09:20:00+08:00″>
          February 5, 2015 at 9:20am
        </span>
        )
      </div>
      <div>
        by
        <span itemprop=”author” itemscope itemtype=”https://schema.org/Person”>
          <a itemprop=”url” href=”https://example.com/profile/janedoe123″>
            <span itemprop=”name”>Jane Doe</span>
          </a>
        </span>
        and
        <span itemprop=”author” itemscope itemtype=”https://schema.org/Person”>
          <a itemprop=”url” href=”https://example.com/profile/johndoe123″>
            <span itemprop=”name”>John Doe</span>
          </a>
        </span>
      </div>
    </div>

Useful Google documentation