<a-scene>
<a-box position="-1 0.5 -3" rotation="0 45 0" ></a-box>
<a-sphere position="0 1.25 -5" radius="1.25" ></a-sphere>
<a-cylinder position="1 0.75 -3" radius="0.5" height="1.5" ></a-cylinder>
<a-plane position="0 0 -4" width="4" height="4" ></a-plane>
<a-sky color="#ECECEC"></a-sky>
</a-scene>
When looking at the code above you notice it looks like HTML. In A-Frame almost everything is based on components. The elements and attributes in the example above are components.