Why PIN important Post in Facebook

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Facebook allows you to pin a single post to the top of your Page's timeline for up to a week or longer. Use this to feature important content, and make it more visible to fans who visit your Page. All new status updates will appear below the pinned post until it is unpinned (or a week elapses), whereupon it will fall into its original chronological position. After creating a post, hover over it until the pencil icon appears, click it and choose 'Pin to Top'. In particular, posts to consider pinning include special announcements, contents, promotions, etc