Short answers, pulled from the story.
Panic! at the Disco formed in 2004 with original members Ryan Ross, Spencer Smith, Brent Wilson, and Brendon Urie. Ross and Smith were classmates at Bishop Gorman High School while Wilson and Urie came from Palo Verde High School.
The debut album A Fever You Can't Sweat Out was released on the 27th of September 2005. The recording process took place over five-and-a-half weeks in College Park, Maryland.
Ryan Ross and Jon Walker left Panic! at the Disco in July 2009 due to creative differences regarding the band's musical direction. They formed a new band called The Young Veins to pursue their own creative paths.
Spencer Smith officially left Panic! at the Disco in April 2015 after struggling with substance abuse issues. The band subsequently became a solo project fronted by Brendon Urie who wrote the fifth album Death of a Bachelor without Smith.
Brendon Urie announced the end of Panic! at the Disco in January 2023 to focus on his family after learning he and his wife were expecting a child. The decision followed the conclusion of the Viva Las Vengeance tour which ran until March 2023.
Panic! at the Disco will reunite to headline the When We Were Young festival in October 2025. The reunion includes Spencer Smith returning to play drums for the first time since 2015.