<p><span class="h-card" translate="no"><a href="https://mastodon.social/@mcc" class="u-url mention">@<span>mcc</span></a></span> <span class="h-card" translate="no"><a href="https://mastodon.social/@cr1901" class="u-url mention">@<span>cr1901</span></a></span> <span class="h-card" translate="no"><a href="https://f.duriansoftware.com/@joe" class="u-url mention">@<span>joe</span></a></span> the square brackets represent an address expression, so if you do `mov rax, rcx` that's just a register move, but `mov rax, [rcx]` is a memory load from the address in rcx. in the vast majority of cases a square bracket expression is used to signify a memory operation, with lea (load effective address) being the notable exception, which loads the result of the address expression itself into the target register.</p>
