Where is it?: Recent Activity is the last box in the left-hand column on your timeline/profile. If you have no recent activity, you won’t see the box.

To hide activity: Click on the x next to a post in the box, and click on “Hide all [story type]…”

To unhide activity: First, click the pencil icon in the top right corner of the box, then click on hidden activity.

Then a box like the one below should appear, Click the “x” next to the things you want to restore to your Recent Activity.

That’s it!
Update 7 (December 15, 2013): With the addition of Facebook’s “Following” button on people’s profiles, some of the information below has changed. The below is outdated, but kept for reference

Event Activity Not Showing Up Under Recent Activity on Timeline: Report It

Update 6 (January 4, 2012): Some users are reporting that some of their recent activity is no longer showing up, like comments on other friends’ posts or event activity on Facebook Timeline. It appears Facebook has now removed the option to display such stories at all on Timeline.  Some users (and I’ve tested myself now) cannot unhide their Event activity if they had hidden it in the past. From now on, stories such as commenting and event activity will appear in the News Feed and Ticker based on your friends’ subscriptions to you.

For example, if you go to a friend’s Timeline, you will not be able to see whose posts they have commented on recently. If you want to find out, you would have to go to Subscribed (at the top) and check “Comments and Likes.” From then on, whenever that friend likes or comments on something, it will appear in the Ticker (above the chat bar on the right side). Facebook recently removed the option to choose whose comments/likes you would see in the News Ticker.

It does not look like Facebook will ever restore commenting/event activity to Timeline. There is a glitch with Event activity that has yet to be fixed… Report It

Edit: I have been doing some testing and look at this:

And after switching to the new profile….

Alright, so event activity should appear on the timeline. We clearly have a problem now….

Update 5 (November 6, 2011): If you are using Facebook timeline, you can edit which types of updates you’ve hidden by clicking on the pencil icon to the right of the Recent Activity box as shown below

If you are looking to hide activity, simply click the “x” that appears when you hover over a recent activity story and click “Hide Similar Activity from Timeline.”

Update 4: Facebook has brought back the Edit Options link at the bottom of my wall. If you have accidentally hid any type of activity on your wall, you can now un-hide it by going to the bottom of your wall, clicking on Edit Options, and clicking the “x” next to the type of story you want to un-hide. Note that the Edit Options link may take a while to propagate to all users once again.

Update 3: Speculation. Some users had reported that some links, such as YouTube videos, they were sharing did not appear on their wall, only on their news feed. These users had also reported that they had clicked on “hide all comment activity.” I believe that there might have been a bug that caused links to disappear when a person hid their comment activity. Facebook has most likely taken the recent activity options off for now while they sort out this bug and hopefully it will be back up soon. Can anyone confirm that they were not able to see their links they had shared after they hid all comment activity? Comment below

Original Post: It looks like Facebook has begun to roll out the “Recent Activity” options to its users. Facebook removed these options and defaulted all recent activity to “on” back in December of 2009. Take a look at what I found earlier this evening:

“Recent Activity” shows recent comments users have made on posts, and recent pages they have liked, as well as public events users are attending and other things. Back in December 2009, Facebook, somehow, decided that it would be always on, and if a user didn’t want a post to show up, they would have to manually remove it each time.

These settings bring more privacy back to Facebook! If a user comments on a friend’s status, and that status was set to friends of friends, by default, all* the user’s friends would see that they commented on that friend’s status, regardless of friendship, in their news feed. Now, users can set it up so that their comments aren’t shown in their recent activity.

I appreciate Facebook bringing back this option. It was annoying to have to go into my wall and remove posts that I didn’t want to show up in my friends’ news feeds.

To unhide a certain type of “recent activity” story on your wall, scroll to the bottom of the wall, click on Edit Options, and click the “x” next to the type of story you want to unhide.

This post has been formatted from its original version. Updates 1 & 2 have been edited into the story/removed.

*Note: Not all users are guaranteed to see the post, depending on each individual’s news feed settings.