Timeline shows two graphs — the public interest graph, and the media interest chart.
Public Interest: Total Interactions
The public interest graph shows total interactions for web articles.
Total Interactions on the Timeline widget is the total number of Facebook Interactions + Twitter Influencer Shares that an article receives.
Each data point in your public interest graph is either an hour or a day, depending on how you've setup your Timeline widget.
Media Interest: Articles Published
The media interest bar chart shows the total number of relevant articles published in your selected timeframe.
Each column in your bar is a count of articles per hour or per day, depending on how you’ve setup your Timeline widget.