What actually is QuickTime and how is it related to .mov?

Oops, wrong article.

QuickTime File Format - Wikipedia, the free encyclopedia.

It's merely an extension signifying a particular format for a movie or video file.

Is it correct to say that Quicktime only has one type of container?

No, it would be more correct to say that MOV file type is the "generic" QuickTime file container. Many file types are supported dependent on the QT app in use and the system's QT codec component configuration. Any data format compatible with a user's QT codec component configuration can be placed into the MOV file container which may support up to 99 tracks of data. Data stored in other file types can be copied to the MOV file container without being transcoded.

That a MOV file must be QuickTime, and QuickTime only has one option for a container: MOV.

Any MOV file may be referred to as a "QuickTime" whether the data contained is supported by the basic OS configuration, supported by Apple components installed as part of user installed applications, or add-on third-party open or proprietary codec components or packages installed by the user. As a result, MOV files created on one system may or may not be compatible with other systems even though the data is contained in the MOV file container. In addition, MOV files created in one version of the QT player (e.g., "muxed" MPEG-2 encoded video placed in an MOV file container by QT 7 Pro) may not be compatible with another QT player app (e.g., QT X player) even though the data format is supported. (I.e., in this example the QT X player does not seem to be programmed to invoke the MPEG-2 codec for MOV or VOB file containers.)

Media formats supported by QuickTime Player

What actually is QuickTime and how is it related to .mov?

QuickTime is a structure (set of compression, decompression, and rendering routines) which is embedded in all current Mac OS X platforms. It can be accessed by any QT-based GUI app like QT 7, QT 7 Pro, QT X, iMovie, FCP, Compressor, GarageBand, SoundTrack, iTunes, Preview, etc. as needed in support of a system's QT codec component configuration. On the other hand, the MOV file extension refer's a generic file container that may contain up to 99 tracks of data supported by the embedded QT structure and codec component configuration. These tracks can contain anything from audio and/or video to text and/or images to sprites and/or 'tweening instructions and are not confined to specific compression formats which are frequently associated with a specific file container or extension. In some whays you might consider it the QT equivalent of the PC's generic legacy AVI file container or the newer MKV file container.

My question is: do all QuickTime containers have the extension MOV? Are there any other types? For instance, is there a QuickTime sound file format with a different extension?

To answer that question you will have to define what you mean by a "QuickTime container." All MOV files are referred to as QT files whether the content is native to a particular Mac OS X system or encoded using a third-party proprietary codec component. Most other extensions refer to the particular type of compressed data or class of data normally contained within the file container. Therefore, if you are using the term "QT container" to refer to files that are natively compatible with QT-based apps, the QT embedded structure, and a particular QT codec component configuration, then there are several that support audio and/or video content. However, since any compressed data can be copied from its original file container to an MOV file container without recompressing the data using the "Save As..." option, I would have to say that the MOV container is, by far, the most common QT file extension—especially if the user has edited the content in any way, shape, or form and then saved the results.

I'm confused. Shouldn't the Wikipedia article state that a file in QuickTime format always comes in a MOV container, and shouldn't the FCP article (quoted above) simply say "The QuickTime File Format"?

Not at all. Your work flow will usually determine the file format. For instance, using QT 7 Pro (or GarageBand) you can create an H.264/AAC video file that ends in an MOV, M4V, or MP4 file container—all depending on how you chose to export the data.