Title: Sheffield RUFC
Content:  Home: the traditional colours are a royal blue and white hoops shirt, navy blue shorts and red socks with white and blue hoops. For the 2019/2020 season Sheffield will be wearing light blue and navy blue hoops, with navy blue shorts and plain red socks to celebrate the centenary of playing at Abbeydale Park. Away: red shirt with navy blue shorts and red socks with white and blue hoops.
Title: Sheffield United F.C.
Content:  Sheffield United have played in red and white stripes for most of their history, but began playing in white shirts and blue shorts. They briefly played in narrow red stripes for the 1890–91 season, before returning to all-white the following year. The stripes returned in the 1892–93 season, with black shorts replacing the blue in 1904. The shirts remained largely unchanged until collars were first removed in 1955, replaced by V-necks until the 1966–67 season (when white socks were also used), and from here on the neck style varied. The traditional red and white stripes remained until the 1974–75 season, when elements of black were added, until the 1979–81 and 82 season kit. This was white with a red 
Title: Sheffield United F.C.
Content:  city of Sheffield's coat of arms from 1965–77, when a new crest was used, introduced by former manager Jimmy Sirrel, but designed apparently over 20 years previously by former player Jimmy Hagan. This consisted of two white crossed swords, or blades, the club's nickname, with a Yorkshire Rose above, on a black background. This is surrounded by a red ring with "Sheffield United F.C." written around the top and "1889", the year the club was founded, underneath. This has been altered very slightly a few times, with a simple black embroidered crest appearing on shirts from 1987–90, and an all-white crest on a red-edged black shield for the 1992–99 seasons, but reverted to its original form in 2000.
Title: Sheffield Eagles
Content:  The club adopted the colours of the original Sheffield Eagles, playing in red, gold and white. The club's shirts have been predominantly red with either a gold or white V across the front. Away shirts vary in colour with some being black or white. The 2020 home shirt is predominantly red, white and gold. The 2020 away kit is a gold and black strip, black shorts and black socks.
Title: 1890–91 Sheffield United F.C. season
Content:  Although United's jersey remained predominantly white, thin red vertical stripes were introduced for the first time, which evolved into the solid red and white stripes that the team still plays in today. The team retained the blue shorts and socks worn in the previous season.
Title: Sheffield United F.C.
Content:  white stripes and black socks with varying trim have been the order of the day, with black shorts for all but the 2002–05 seasons, when white and then red were tried. The club also every few seasons opt to put thin black stripes between the red and white stripes. Sheffield United's home colours were the inspiration for the kit of Irish club, Derry City. In 1934, Derry City adopted the stripes, while Billy Gillespie was manager of the club, in recognition of Gillespie's achievements at Sheffield United. The first time a crest appeared on the shirt was in the 1891–92 season, when a red crest appeared on the white shirt, but this disappeared the following season. United used 
Title: 2007–08 Sheffield United F.C. season
Content:  Sheffield United maintained both their kit manufacturing agreement with French company Le Coq Sportif, who produced a new home kit for the season, and their kit sponsorship agreement with American bank Capital One. A new away strip with fluorescent green shirts and black shirts and socks with fluorescent green trim was also introduced.
Title: 2008–09 Sheffield United F.C. season
Content:  Sheffield United continued their kit manufacturing agreement with French company Le Coq Sportif, who produced a new kit for the season, designed by United season ticket holder Ben Frost. A black away kit with silver trim, chosen by the club's players, was also introduced. The previous season's black and fluorescent green away kit was retained as the third kit. The club ended their kit sponsorship agreement with American bank Capital One at the end of the previous season. The new kit sponsor for the season was visit Malta.com.
Title: 2013–14 Sheffield United F.C. season
Content:  At the end of July, United unveiled new home and away kits for the following season. Produced by Macron, the home kit maintained the clubs traditional red and white stripes, albeit with the addition of a solid red panel across the shoulders and neck. The away kit was a complete change from previous seasons, consisting of an all yellow shirt with green trim plus green socks and shorts. The club also announced that the home kit would be sponsored by Spanish video game developer VSports, and the away kit would bear the logo of Chinese real estate company Top Spring. The following day the club also announced a new secondary shirt sponsor, with the logo for video game Football Manager appearing on the back of both the home and away shirts for the following season. In September United announced a secondary sponsor, with mobile phone distributor Shebang's logo appearing on the shorts of both the home and away kit.
Title: History of Sheffield United F.C.
Content:  fifth. This season was the first time that the club introduced a red stripe to their shirts, having played their first season in all-white shirts. Unhappy at being overlooked for the Football Alliance and no longer satisfied with the Midland, they then competed the following season in the Northern League finishing third. At the end of the season they applied to join the Football League First Division, which was expanding from 14 to 16 clubs for the 1892 season, but polled only 5 votes and were instead admitted as one of the twelve founder members of the Second Division with the Alliance clubs, replacing Birmingham St George's which had folded.

Question: What color is Sheffield United F.C?
Answer: red.
red color.