 shard, a set of 100 validators get selected as attesters. The header of a block together with at least 67 of the attesting signatures can be published as an object that gets included in the "main chain" (also called the beacon chain).</p>
<p>Note that there are now several "levels" of nodes that can exist in such a system:</p>
<ul>
<li>Super-full node - downloads the full data of the beacon chain and every shard block referenced in the beacon chain.</li>
<li>Top-level node - processes the beacon chain bloc