Short answers, pulled from the story.
An anthology series presents a different story and a different set of characters in each episode, season, or segment. Some anthology series feature a permanent ensemble of actors who play new roles each week, as Four Star Playhouse did from 1952 to 1956, while others bring in an entirely fresh cast each installment.
The word anthology derives from Ancient Greek, coined by the poet Meleager of Gadara around 60 BCE. He originally called his poetry collection Stephanos, meaning garland, because in Greek culture flowers symbolized the finer sentiments that only poetry can express. The collection was later retitled anthology.
The Collier Hour, broadcast on the NBC Blue Network from 1927 to 1932, is recognized as radio's first major dramatic anthology series. It adapted stories and serials from Collier's Weekly and initially aired on Wednesdays before moving to Sundays to avoid spoiling stories still appearing in that week's magazine.
American Horror Story, which debuted in 2011, introduced the season-long anthology format in the United States, making each full season a standalone story rather than varying the narrative episode by episode. Its success prompted similar season-long anthologies including American Crime Story and True Detective.
Four Star Playhouse, which debuted on CBS in fall 1952, rotated among a permanent company of stars, each appearing in a different drama each week. Dick Powell, Charles Boyer, and David Niven were the core three stars, with Ida Lupino later joining as a de facto fourth, though unlike the others she held no ownership stake in the production company. The show ran until 1956.
The final episode of Suspense was broadcast on the 30th of September 1962, a date traditionally regarded as marking the end of the old-time radio era. Suspense had run continuously since 1942, making it one of the longest-running radio anthology series.