A timeline is a Twitter term used to describe a collected stream of Tweets listed in real-time order. This brief article explains a little more about where you see timelines on your Twitter account.
When you log in to Twitter, you'll land on the Tweets timeline view of your homepage, as shown in the image below.
Note: If you see Tweets in your timeline from users you don't follow, check to see if they're Retweets. It's likely someone you do follow chose to re-broadcast that message because they found it interesting. Retweets do show up in your timeline, unless you have them turned off for a particular user.
Check out our Tweet & DM Troubleshooting section for solutions to common problems.