HLN is an American basic cable network. Owned by CNN Worldwide, the network primarily carries true-crime programming, recently drifting away from limited live news programming.

The channel was originally launched on January 1, 1982, by Turner Broadcasting as CNN2 (later renamed Headline News or CNN Headline News), a sister network to CNN that broadcast a looping, half-hour cycle of segments covering various news topics. In 2005, HLN began to diverge from this format and air more personality-based programs, including a primetime block featuring pundits such as Glenn Beck and legal commentator Nancy Grace. In the mid-2010s, HLN repositioned itself as a social media-centric network, highlighting headlines popular on social networks, and introducing social media-themed shows. Under CNN president Jeff Zucker, the channel began to backpedal on this programming in 2016, gradually shifting to a focus on crime, "regional" headlines, and entertainment stories (in contrast to CNN's current focus on politics) during its daytime programming, with true crime programs airing at all other times.

With the 2022 merger of CNN parent WarnerMedia and Discovery Inc. to form Warner Bros. Discovery, HLN became a sister to Discovery's true-crime channel Investigation Discovery (ID). In December 2022, then-new CNN president Chris Licht announced that HLN would abandon original live news programming entirely as part of a reorganization, with the network now being overseen by ID's staff. For contractual reasons, HLN continues to air news content daily through a simulcast of CNN's early morning programming. The network's schedule outside of that has primarily featured true crime programs as before, in addition to occasional marathons of crime and legal dramas from the Warner Bros. Television library.

As of November 2023^[update], HLN is available to approximately 68,000,000 pay television households in the United States-down from its 2011 peak of 100,000,000 households. Since the mid-2000s, HLN has been available internationally on pay television providers in parts of Asia, the Caribbean, Latin America, the Middle East, North Africa, and Canada.

The channel was launched at midnight Eastern Time on January 1, 1982, as CNN2. The channel's launch was simulcast nationwide on sister networks CNN and Superstation WTBS (now simply TBS), starting at 11:45 p.m. on December 31, 1981, as a preview for cable providers that had not yet reached agreements to carry CNN2. Following a preview reel by original CNN anchor Lou Waters and an introduction by founder and then-Turner Broadcasting CEO Ted Turner, Chuck Roberts (who would become the channel's longest-serving news anchor, with a 28-year career with CNN2/Headline News that lasted until his retirement on July 30, 2010) and Denise LeClair anchored the channel's first newscast.

Originally, the channel's programming was formatted around the idea that a viewer could tune in at any time of day or night (instead of having to wait for the once- or twice-daily national news segments in local newscasts, or morning or evening network news programs), and receive up-to-date information on the top national and international stories in just 30 minutes. This "Headline News Wheel" format—which was derived from the "wheel" segment schedules used by all-news radio stations and repeated each half-hour—featured national and world news at the top of the hour (:00/:30), business and personal finance reports ("Dollars and Sense") at :15/:45 after the hour; sports scores and headlines ("Headline Sports") at :20/50 after; and lifestyle reports at :25/:55 after. The :25/:55 lifestyle segment was designed to allow local cable systems the option of pre-empting it with a local headline "capsule" from an associated regional cable news channel or a local television station. Another regular feature, the "Hollywood Minute", was often fitted-in after the "Headline Sports" segment. In the channel's early years, a two-minute recap of the hour's top stories, the "CNN Headlines," would run after the sports segment.

On August 9, 1982, what had been called "CNN2" for its first eight months on the air was renamed Headline News, though the network would be referred to on-air as "CNN Headline News" for much of the mid-1980s. (Beginning around 1988, some newspapers began referring to the channel as "HLN Headline News.") By 1992, the channel was often abbreviated as "HN" (the channel would later incorporate a die-cut "HN" block design within the original variant of its third logo when it was introduced in 1989, before it was fully supplanted by the wordmark that accompanied it in 1992, which was later italicized). During its first year, Headline News had a competitor in the form of ABC/Group W's Satellite News Channel, which operated from June 21, 1982, to October 27, 1983. After its shutdown, SNC's satellite slot was then purchased by Ted Turner to expand Headline News' reach further into additional homes. Shortly after, sister station WTBS handed over production duties for their NewsWatch news capsules to Headline News (resulting in these interstitials switching from an in-studio anchor format to being presented in voiceover only), and at various times, other specialized news capsules produced by Headline News aired as well; the NewsWatch segments as well as daily Headline News simulcasts were phased out on TBS's local and national feeds in 1996 after the Federal Communications Commission (FCC) relaxed regulatory requirements on public affairs programming.

Jon Petrovich was hired in the mid-1980s by Turner to lead Headline News. In 1990, Headline News developed Local Edition, a six-minute-long local newscast, whose content was produced by a local broadcast station in the participating market, airing at the end of each half-hour of Headline News' rolling news block. The channel included the "CNN" branding in its name intermittently for most of its history, before being incorporated on a regular basis from 1997 to 2007 (though an alternate logo without the CNN logo was used for news broadcasts through 2001).