Twitter is introducing custom timelines, the ability for users to create a timeline to follow based on words, phrases, hashtags, and more. Custom timelines are public, and have their own page on twitter.com so they're easy to share. Twitter wants people to use custom timelines for conversations about specific topics, and they help you gather the best tweets about an event or topic in one place, according to a post on Twitter's developer blog:
Share the best Tweets about a topic you care about, or an event –– planned or unplanned –– that’s happening right now. Whether you want to collect the best Tweets about a TV show or help people find the latest information about fast-moving real-time situations, custom timelines let you give everyone a place to follow along.
An API is also being released that will let developers use custom timelines in their products. Developers can program timelines based on their own logic, or make tools to help users create their own timelines.
Currently, you need to use the TweetDeck web app in order to create a custom timeline. To create one, navigate to tweetdeck.twitter.com and click the '+' in the sidebar. The item on the bottom right side of the menu will say Custom Timeline if Twitter has rolled it out to you. Click it, then enter a name for your timeline, as well as the parameters that you want it to follow. Drag tweets into your custom timeline to populate it. Twitter expects every TweetDeck user to get custom timeline capabilities over the next several days.
Source: Twitter developer blog