Elements in HTML can either be block (takes up the full-width available) or inline (only takes as much width as necessary).
Header elements (<h1>) and paragraph elements (<p>) are common block elements. Another one is <div>, which stands for "division" or "section". Anything enclosed between div tags <div></div> is considered a single "container" in the document.
Link elements (<a>) and image elements (<img>) are common inline elements. Another one is <span>. Anything enclosed between span tags <span></span> is considered a single container and can be treated differently than a paragraph or div that it might be contained within.
We will talk much more about <div> and <span> when we learn styling in the CSS portion of this course.