A newscast is a television or radio show about current news events. Some TV channels feature a half hour newscast at the end of every week day.
An all-news cable TV channel is basically nothing but newscasts, with news headlines, analysis of the news, and commentary about current events. Traditionally, network television stations scheduled one or two newscasts per day, broadcasting that day's biggest news. The word newscast is North American, and it first appeared (referring to radio news) around 1930, modeled on the earlier broadcast.