As discussed in over in another thread....a specific thread to discuss the Short Treks!
Episode 101 "Runaway" (released 10/04/2018)
Setting: 2257, during Season 2 of Star Trek: Discovery
"Runaway" is set sometime early in Season 2, as Tilly is shown here as an Ensign, with the Starfleet Medal of Honor visible in her quarters (she was awarded both of these at the end of the Season 1 finale). It shows Tilly's first meeting with Po, who later reappears in the first half of Discovery's Season 2 finale, "Such Sweet Sorrow" Part 1.
Episode 102 "Calypso" (released 11/08/2018)
Setting: The distant future
"Calypso" is, currently, a sort of coda to the entire franchise. Set aboard the USS Discovery, a thousand years after the ship was "abandoned," this episode has no other ties to anything else in the Star Trek universe.
Episode 103 "The Brightest Star" (released 12/06/2018)
Set 17 years before the pilot episode of Star Trek: Discovery, "The Brightest Star" is a prequel that tells the story of how Saru left his homeworld and came to serve in Starfleet. This Short Trek is a tie-in to the Discovery Season 2 episode "The Sound of Thunder."
Episode 104 "The Escape Artist" (released 01/03/2019)
A Harry Mudd-centric story which appears to be set sometime after Mudd's appearances in Season 1 of Star Trek: Discovery. "The Escape Artist" is also something of a loose tie-in to the TOS episode "I, Mudd."
Episode 201 "Q&A" (released 10/05/2019)
Setting: 2254 (approximately)
"Q&A" is set exclusively aboard Captain Pike's USS Enterprise, and depicts Ensign Spock's first day aboard as a member of her crew. This places this story sometime prior to the TOS pilot episode "The Cage," which was set in 2254 (three years before Discovery Season 1).
Episode 202 "The Trouble with Edward" (released 10/09/2019)
Setting: Late 2250s/early 2260s
Opening with a brief cameo by Captain Pike, "The Trouble with Edward" actually follows the first command mission of one of Pike's officers who has been promoted to Captain of her own ship. This Short Trek isn't connected to any other series, but does serve as a loose prequel to the TOS episode "The Trouble with Tribbles."
Episode 203 "Ask Not" (released 11/14/2019)
Setting: Late 2250s/early 2260s
"Ask Not" features a young Starfleet cadet, tasked with guarding Captain Pike, who has been arrested. When Starbase 28 comes under attack, she has to decide whether or not she will release him from custody to help with the defense. This Short Trek isn't connected to any other series.
Episode 204 "The Girl Who Made the Stars" (released 12/12/2019)
Setting: Early 2230s
Set when Michael Burnham is just a kid, a lightning storm in space scares her, and her dad tries to ease her fear by telling her a story about a brave little girl who faced her own fears head on.
Episode 205 "Ephraim and Dot" (released 12/12/2019)
Ephraim, a humble tardigrade, is flying through the mycelial network when an unexpected encounter takes her on a bewildering adventure through space.
Episode 206 "Children of Mars" (released 01/09/2020)
Setting: 24th century
Little information about this Short Trek has been released as of yet. It will be a prequel episode to Star Trek: Picard.