Your Activity page is a collection of your activities on IMDb from your ratings, reviews, lists, Watchlist, Check-ins, polls, and badges you earn based on your activity on IMDb.
See also: What's the difference between an IMDb page and user profile?
If you mark your Watchlist, lists, ratings, etc. as private, we'll respect your setting and it will only be visible while logged into your IMDb account. To quickly view what's been marked as private, we recommend viewing your Activity page while logged out of IMDb. Even if your lists and ratings are marked as private, roll-ups of that data may be aggregated and visible as badges or other recognition. When your information is public, you get access to awesome features - like being able to compare your ratings against other IMDb users. See Col Needham's activity page for an example.
Badges are accomplishments that we have designated as worthy of earning a badge. Everyone has a Tenure badge based on how long they have had an account on IMDb, and other badges are either automatically assigned or earned. Available badges are on our Badge Detail page.
The section will appear when you add something to the Watchlist or Check-In for the first time.
To change your ratings privacy, click your name from the right hand of the screen and select "Your Ratings" from the drop down menu. Click the 3 vertical dots and select "Settings" from the menu, then select your preferred privacy setting, and click "Save".
You'll need to update the privacy settings for each individual list. Select your name from the right hand and click "Your Lists" from the drop down menu, click "Settings" and select your privacy setting.
Navigate to your Watchlist, click "Edit", and then select "Settings" to update your Watchlist privacy and click "Close".
Check-Ins are currently always public and cannot be made private.
Recent Polls are currently always public and cannot be made private.
If you set your ratings to public, and visit someone else's activity page that also has public rating, you can see an interesting chart on how their tastes compare to yours. Here's our founder Col Needham's activity page. The page will do a Pearson Correlation between two users ratings and display a statistic about how much your tastes overlap. Note that this feature is under development and the number could change dramatically and you should not make potentially life-altering decisions based on this rather arbitrary number. It will also display a set of films for which your ratings diverged form each most dramatically.