user791: Is it a codec? I don't think so; I believe it uses MPEG4/H.264 for video and AC3 for audio.
Is it a container format? Doesn't seem to make a huge amount of sense; there are enough out there already and it's likely that a suitable one already exists.
Is it simply a specification that specifies a particular combination of pre-existing technologies? But this would imply that AVCHD files could also be called something else, like "MPEG4 container with H264/AC3 inside".
So what exactly does AVCHD mean?

user525: I think this image from Wikipedia says it best:

AVCHD is not a codec, but it is also not just a container.
Just like "every other" container, AVCHD features:

Video streams
Audio streams
Subtitles

But in addition, for example:

Playlists
Menu presentation (like in a DVD)


Is it simply a specification that specifies a particular combination of pre-existing technologies?

Yes.

But this would imply that AVCHD files could also be called something else, like "MPEG4 container with H264/AC3 inside".

But who would like to call it that? Several other specifications take already existing specifications, remix them, and they aren't called "Open Source Container format for XYZ".
I think it's a "one format fits it all" mentality, which is why you'll find AVCHD on many consumer devices.

791: <p>Is it a codec? I don't think so; I believe it uses MPEG4/H.264 for video and AC3 for audio.</p>

<p>Is it a container format? Doesn't seem to make a huge amount of sense; there are enough out there already and it's likely that a suitable one already exists.</p>

<p>Is it simply a specification that specifies a particular combination of pre-existing technologies? But this would imply that AVCHD files could also be called something else, like "MPEG4 container with H264/AC3 inside".</p>

<p>So what exactly does AVCHD mean?</p>
 525: <p>I think this image from Wikipedia says it best:</p>

<p><img src="https://upload.wikimedia.org/wikipedia/commons/thumb/3/3c/AVCHD_actual_file_structure.svg/380px-AVCHD_actual_file_structure.svg.png" alt=""></p>

<p>AVCHD is <strong>not a codec</strong>, but it is also <strong>not just a container</strong>.</p>

<p>Just like "every other" container, AVCHD features:</p>

<ul>
<li>Video streams</li>
<li>Audio streams</li>
<li>Subtitles</li>
</ul>

<p>But in addition, for example:</p>

<ul>
<li>Playlists</li>
<li>Menu presentation (like in a DVD)</li>
</ul>

<blockquote>
  <p>Is it simply a specification that specifies a particular combination of pre-existing technologies?</p>
</blockquote>

<p>Yes.</p>

<blockquote>
  <p>But this would imply that AVCHD files could also be called something else, like "MPEG4 container with H264/AC3 inside".</p>
</blockquote>

<p>But who would like to call it that? Several other specifications take already existing specifications, remix them, and they aren't called "Open Source Container format for XYZ".</p>

<p>I think it's a "one format fits it all" mentality, which is why you'll find AVCHD on many consumer devices.</p>
