WordPress has some of this functionality built-in, and it’s often overlooked. It’s not super sophisticated, like a true version control system, but it’s better than nothing.
When you create posts or pages, WordPress will save previous versions of something you’ve worked on more than once. These are called revisions. Find a post or page that you’ve done many edits to, and open it in the editor. Take a look near the top right in the “Publish” box. This box may contain something like “Revisions: 4”. Click the “browse” link next to it, and you’ll get to a screen where you can see before/after changes, and restore a particular one if you want.
Don’t see any “Revisions” on the page? Go to the top of the page, and click “Screen Options” at the upper right. If you see a “Revisions” option there, click it, and then you should be able to look at any revisions.
If you still don’t see any of that, your post/page may not have any revisions yet, or maybe some plugin has disabled (or deleted) revisions.
Apart from that, there are a number of WordPress plugins that deal with revisions in a bit more detail. Here’s one you can try.
Caveat – I haven’t used it. I tend to delete revisions to save database space, although on occasion I have used the revisions feature to restore something.
There are people who want to keep watch over their site if they have many contributors, or maybe they’re simply control freaks. 🙂 This isn’t exactly an audit trail, but it looks like it provides records of many activities: