Should websites live in /var/ or /usr/ according to recommended usage?

According to a guide on the Linux directory structure, /usr/ is for application files, and /var/ is for files that change (I assume this means "files that belong to the applications"). Is this correct?

If this is the case then I'm a little torn between using either. A website is an application (if it's dynamic, so to speak), but in other cases it is just a collection of files used by Apache.

The default www dir lives in /var/www/, so should we follow suit by using /var/websites/ (or something similar), or choose /usr/websites/ since they could be applications?

This is a very trivial question, but it's bugging me nonetheless. For our case, I'm leaning toward /usr/web or something like that, since our websites are all applications.

Update:

This is for our company websites; it's not a shared hosting server, so we don't need to worry about separating them in /home/ or anything like that.

According to the FHS, /usr is for shareable, read-only data - not where you want to put the website. This is where you should put your code (for example Fedora does this for Wordpress). See also the web assets packaging guide for Fedora.

/var is "variable data files. This includes spool directories and files, administrative and logging data, and transient and temporary files." -- better, but still not quite right -- but a lot of systems will use /var/www, so even if you're wrong to put it there you're in good company.

/srv is for "site-specific data which is served by this system." -- which seems like a good match, but is much less common than /var/www.

The other common place to put the site files is under /home -- by creating a special user called website or such, then placing the files inside that user's homedir (e.g., /home/website).

Take a look at the Filesystem Hierarchy Standard (Wikipedia). I myself use /srv/web/$domain/{htdocs,logs,cgi-bin,...}.