Tagging and sharing are two intertwined features of the Facebook Timeline: you can tag and share at the same time or perform only one of these tasks. Tagging is the act of tying a user account to a piece of content on Facebook, whereas sharing is the act of placing content on a user's Timeline to appear in that user's friends' Timelines.

Tagging Ties Users to Content

Tagging a person in a status update, Timeline post or media item creates a link from that person's Timeline to the tagged content. Tags are commonly used as a way to mention or publicly message other users through the Timeline as well as connect user accounts to photo and video content that features or references the user. Tags can be activated on the Timeline by typing the "@" symbol followed by the user name and in media content by clicking the "Tag" button. However, overusing and inappropriately using the tag feature is known to frustrate some users.

Sharing Posts Content for Others

Sharing is the act of posting content to your Timeline or someone else's Timeline for other Facebook users to see. You can share content posted through your account and content that appears in your Timeline by clicking the "Share" link beneath the post and specifying the intended audience. Status updates are the de facto shared content type as they are automatically shared on a user's Timeline. Users can also share website links, images and video content.