The Watch list is a list, where you can store films that you would like to watch.
You can add any film from its page by clicking on the watch list icon.
When you want to watch a choosen movie you have previously saved simply go back to your watch list and watch it.
You can access your watch list by clicking on the "playlists" section on your profile page.
If you want to share your collection, use "Share" or "Share with friend" buttons.
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