Title: That '70s Show (season 1)
Content:  The first season of That '70s Show, an American television series, began August 23, 1998, and ended on July 26, 1999. It aired on Fox. The region 1 DVD was released on October 26, 2004. The season is set between 1976 and 1977. The first twelve episodes and the 23rd episode were set in 1976, then the series transitioned to 1977 for the remainder of the season.
Title: List of That '70s Show episodes
Content:  That '70s Show is an American comedy television series that originally aired on Fox for 200 episodes and four specials across eight seasons, from August 23, 1998, to May 18, 2006. The series spans the years 1976 through the end of 1979. Series screenwriters included Philip Stark, Mark Hudis, Jeff and Jackie Filgo, Will Forte, Gregg Mettler, Dean Batali, and series creators Bonnie and Terry Turner. All episodes following the pilot were directed by David Trainer. For seasons 5–8, episodes were titled after song names from various 1970s British rock bands: fifth season episodes are named after songs by Led Zeppelin, sixth season titles are The Who songs, all seventh season titles are from The Rolling Stones and, except for the finale, eighth season titles are Queen songs. The entire series of 200 episodes has been released on Regions 1, 2 and 4 DVD, and in 2015, the series was released on Blu-ray.
Title: That '70s Show
Content:  The show was set in May 1976 in the August 23, 1998, premiere. After 12 episodes, the series transitioned to 1977. The 23rd episode, "Grandma's Dead", was also set in 1976, because it was supposed to be the season finale of season 1. The show remained in 1977 for the next two seasons. Near the end of the third season, the series transitioned to 1978 until early in the sixth season. The remaining episodes took place in 1979, and the series finale abruptly ends during a New Year's Eve party as the characters reach "one" during a countdown to January 1, 1980.
Title: That '70s Show (season 6)
Content:  The sixth season of That '70s Show, an American television series, began October 29, 2003, and ended on May 19, 2004. It aired on Fox. The region 1 DVD was released on May 8, 2007. This season is set in 1978 for the first seven episodes of the season. The series transitions to 1979 beginning with the eighth episode of the season ("I'm a Boy"). All episodes are named after songs by The Who.
Title: That '70s Show (season 7)
Content:  The seventh season of That '70s Show, an American television series, began September 8, 2004, and ended on May 18, 2005. It aired on Fox. The region 1 DVD was released on October 16, 2007. This season is set entirely in 1979. This is the last season to feature Topher Grace and Ashton Kutcher as regulars. Grace leaves the show at the end of the season to star in Spider-Man 3, and Kutcher to star in The Guardian. However, Kutcher appears five times in the next season as a "Special Guest Star", and Grace makes an uncredited cameo in the series finale. All episodes are named after songs by The Rolling Stones.
Title: That '70s Show (season 5)
Content:  The fifth season of That '70s Show, an American television series, began September 17, 2002, and ended on May 14, 2003. It aired on Fox. The region 1 DVD was released on October 17, 2006. This season is set entirely in the year 1978. All episodes are named after songs by Led Zeppelin.
Title: That '70s Show
Content:  That '70s Show is an American television period sitcom that originally aired on Fox from August 23, 1998, to May 18, 2006. The series focuses on the lives of a group of six teenage friends living in fictional Point Place, Wisconsin, from May 17, 1976, to December 31, 1979. The main teenage cast members were Topher Grace, Mila Kunis, Ashton Kutcher, Danny Masterson, Laura Prepon, Wilmer Valderrama, and Lisa Robin Kelly. The main adult cast members were Debra Jo Rupp, Kurtwood Smith, Don Stark, Tommy Chong, and Tanya Roberts. In 1999, the show was remade by the ITV network in the United Kingdom as Days Like These using almost verbatim scripts with minor changes to cultural references.
Title: That '70s Show (season 3)
Content:  The third season of That '70s Show, an American television series, began October 3, 2000, and ended on May 22, 2001. It aired on Fox. The region 1 DVD was released on November 15, 2005. The majority of this season is set in 1977, although the year changed to 1978 for the final four episodes of the season.
Title: That '70s Show (season 2)
Content:  The second season of That '70s Show, an American television series, began September 28, 1999, and ended on May 22, 2000. It aired on Fox. The region 1 DVD was released on April 19, 2005. This season is set entirely in the year 1977.
Title: Episode 7 (Twin Peaks)
Content:  "Episode 7" was first broadcast on the ABC Network on May 23, 1990. In its initial airing, it was viewed by 12.6 percent of US households, representing 22 percent of the available audience; it was the most-viewed broadcast in its time-slot. These ratings marked an increase from the previous episode, which had attracted 10.6 percent of the population and 17 percent of the available audience. Writing for The A.V. Club, Keith Phipps rated the episode an "A", finding that the multiple cliffhanger plot threads worked well and did not seem over the top or self-parodying. Phipps felt that the first season was "a near-perfect 

Question: when did the first episode of that 70s show air?
Answer: August 23, 1998.
August 23, 1998.