Title: The Flash (season 4)
Content:  The fourth season of the American television series The Flash, which is based on the DC Comics character Barry Allen / Flash, premiered on The CW on October 10, 2017, and ran for 23 episodes until May 22, 2018. The season follows a crime scene investigator with superhuman speed who fights criminals, including others who have also gained superhuman abilities. It is set in the Arrowverse, sharing continuity with the other television series of the universe, and is a spin-off of Arrow. The season is produced by Berlanti Productions, Warner Bros. Television, and DC Entertainment, with Andrew Kreisberg and Todd Helbing serving as showrunners. The season was ordered in January 2017, and filming began that July. Grant Gustin stars as Barry, with principal cast members Candice Patton, Danielle Panabaker, Carlos Valdes, Keiynan Lonsdale, Tom Cavanagh, and Jesse L. Martin also returning from previous seasons, and are joined by Neil Sandilands. The series was renewed for a fifth season on April 2, 2018.
Title: The Flash (season 4)
Content:  The season began airing on October 10, 2017, on The CW in the United States, and on CTV in Canada. The season concluded on May 22, 2018. Sky One acquired the rights to air the season in the UK & Ireland, airing it alongside the other Arrowverse shows. The season premiered October 17.
Title: The Flash (season 4)
Content:  Filming for the season began on July 4, 2017, in Vancouver, British Columbia, and concluded on April 21, 2018. Kevin Smith returned to direct an episode in January 2018.
Title: The Flash (season 4)
Content:  The season was made available for streaming on Netflix in late May 2018, soon after the season finale aired. It was released on Blu-ray on August 28, 2018.
Title: The Flash (season 4)
Content:  The review aggregator website Rotten Tomatoes reported a 80% approval rating with an average rating of 6.95/10 based on 19 reviews. The website's consensus reads, "After an unsteady turn in season three, The Flash returns to its roots with a fourth season packed with humor, spectacle, and a whole lot of heart." Reviewing the first two episodes of the season, Allison Keene writing for Collider.com, felt the premiere "wipes the slate clean, fixing a lot of the issues that plagued the end of the last season, and setting up a much more toned-down storyline. Most importantly, it's brought back some fun." She added that with a "streamlined team," the core characters now have time to interact and have meaningful plot 
Title: Flashpoint (TV series)
Content:  January 21, 2011, it was announced that CBS would air 7 of the 18 episodes from Season 4, as well as the remaining 6 episodes from Season 3 not yet shown on CBS, during the summer of 2011. Due to the cancellation of CHAOS, the remaining episodes from Season 3 of Flashpoint were shown on CBS starting May 6, 2011. The remaining 11 episodes from season 4 began airing on ION Television in October of that year. Filming of season four took place between February 14 and September 15, 2011. On May 9, 2011, CTV announced that the fourth season would begin 
Title: The Flash (season 4)
Content:  • Britne Oldford as Shawna Baez / Peek-a-Boo • Dominic Burgess as Ramsey Deacon / Kilg%re • Sugar Lyn Beard as Rebecca Sharpe / Hazard and Clifford DeVoe / Thinker • Chelsea Kurtz as Mina Chaytan / Black Bison • Violett Beane as Jesse Chambers Wells / Jesse Quick • Danny Trejo as Josh / Breacher • Vito D'Ambrosio as Anthony Bellows • Emily Bett Rickards as Felicity Smoak • Riley Jade Berglund as Joanie • Matt Afonso as Weeper • Stephen Amell as Oliver Queen / Green Arrow and Dark Arrow • Victor Garber as Martin Stein / Firestorm • Caity Lotz as Sara Lance / White Canary • Chyler 
Title: The Flash (season 4)
Content:  Goldberg as Dave Ratchet / Big Sir • Derek Mears as Sylbert Rundine / Dwarfstar • Paul McGillion as Earl Cox • Miranda MacDougall as Izzy Bowin / Fiddler  and Clifford DeVoe / Thinker • John Wesley Shipp as Jay Garrick / The Flash • Leonardo Nam as Matthew Kim / Melting Point • Max Adler as Jaco Birch / Hotness • Bethany Brown as Janet Petty / Null • Arturo Del Puerto as Edwin Gauss / Folded Man and Clifford DeVoe / Thinker • Katie Cassidy as Laurel Lance / Siren-X • David Ramsey as John Diggle and Clifford DeVoe / Thinker • Victoria Askounis as young Caitlin Snow
Title: The Flash (season 4)
Content: Grant Gustin as Barry Allen / Flash ; Candice Patton as Iris West ; Danielle Panabaker as Caitlin Snow / Killer Frost ; Carlos Valdes as Cisco Ramon / Vibe ; Keiynan Lonsdale as Wally West / Kid Flash ; Neil Sandilands as Clifford DeVoe / Thinker ; Tom Cavanagh as Harry Wells ; Jesse L. Martin as Joe West 
Title: The Flash (2014 TV series)
Content:  The complete first season was first released on Blu-ray and DVD in Region 1 on September 22, 2015, the second season on September 6, 2016, the third season on September 5, 2017, the fourth season on August 28, 2018, and the fifth season on August 27, 2019. Each season release contains additional features, which include: making-of featurettes, episode commentaries, deleted scenes, gag reels, and Comic-Con panels. The second, fourth and fifth season boxsets include the Arrowverse crossover episodes from the other connected television series, as well as commentary on those episodes. On Netflix in the United States, the first season became 

Question: how many episodes is season 4 of the flash?
Answer: 23 episodes.
19.
23.