user133916: I would know what does Bitcoin verify when you download a block.
Are the transactions verified too, or not? If they are, will it be the case for their signatures?
Best wishes.

user208: It depends what kind of software you're talking about.
A full node, by definition, verifies all consensus rules for newly received blocks and their transactions, including:

Proof of work
Difficulty adjustment
Subsidy (do miners not print too much money)
Double spending (do transactions not spend anything already spent)
Transaction balance (do transactions not spend more than they send)
Resource limits (block weight limit, op count limits)
Signature validity
...

Other software that interacts with the Bitcoin network may verify whatever it likes - ranging from all of the above, to some subset, or nothing at all and just trusting what other nodes or servers give it.

133916: <p>I would know what does Bitcoin verify when you download a block.</p>
<p>Are the transactions verified too, or not? If they are, will it be the case for their signatures?</p>
<p>Best wishes.</p>
 208: <p>It depends what kind of software you're talking about.</p>
<p>A full node, by definition, verifies all consensus rules for newly received blocks and their transactions, including:</p>
<ul>
<li>Proof of work</li>
<li>Difficulty adjustment</li>
<li>Subsidy (do miners not print too much money)</li>
<li>Double spending (do transactions not spend anything already spent)</li>
<li>Transaction balance (do transactions not spend more than they send)</li>
<li>Resource limits (block weight limit, op count limits)</li>
<li>Signature validity</li>
<li>...</li>
</ul>
<p>Other software that interacts with the Bitcoin network may verify whatever it likes - ranging from all of the above, to some subset, or nothing at all and just trusting what other nodes or servers give it.</p>
