Standard HTML

  • picture - <picture> element surrounding a <source> tag for each required srcset, and a fallback <img>:

      <picture> 
        <source srcset="..." sizes="..." media="..." type="...">
        <source srcset="..." sizes="..." media="..." type="...">
        (...)
        <img src="...">
      </picture
    
  • img - a single <img> tag with a srcset entry:

    <img src="..." srcset="..." sizes="..." alt="..." width="..." height="...">
    
  • auto - Supply an img tag when you have only one srcset, otherwise supply a picture tag.