On Wednesday, the Cable News Network will commemorate its 25th anniversary with a prime-time special on the 25 defining moments of the past 25 years.

Hosted by CNN’s Anderson Cooper, Paula Zahn and Aaron Brown, CNN’s “Defining Moments: 25 Stories that Touched Our Lives” will air as a two-part special on Wednesday from 8 to 9 p.m. and then from 10 to 11 p.m. A special anniversary edition of “Larry King Live,” which is celebrating its 20th year, will air from 9 to 10 p.m.

The quarter-century celebration is also taking place online. Beginning this week, CNN.com will offer a number of interactive services including a feature that will allow users to rank the most significant news events and newsmakers of the past 25 years.

CNN, which signed on the air as the world’s first 24-hour news network on June 1, 1980, in fewer than two million U.S. households, is available today in more than 89 million U.S. homes and, internationally, reaches more than 160 million households. CNN’s combined networks and services reach more than 2 billion people in more than 200 countries around the world.