The flag has used two different color schemes with the letter "W" on a solid background, and there is a loss indicator flag with a letter "L". Additionally, the flags have been complemented by different color schemes of indicator lights. The flag has become a very symbolic emblem for devout Cubs fans. Some retailers sell slightly different versions that also have the Cubs logo at the bottom.
It is customary to fly flags from sunrise until sunset, unless they are directly illuminated. At the beginning of each day, the cross-shaped "masthead" atop the centerfield scoreboard displays the American flag at the top, and three strands of flags bearing the team colors and city names of each of the National League clubs, one strand per Division in order of that day's standings. Immediately after the game, one of the strands of flags is lowered, and either the W or the L-lettered flag is raised in its place. The W-lettered flag is raised on the left field side of the board, above the blue light that also indicates a win. The L-lettered flag is raised on the right field side of the board, above the white light that indicates a loss. Once the Win or Loss Flag has been raised, the other flags are lowered and also stowed away inside the scoreboard. The symbolism of the flag now serves a wide variety of purposes. It is commonly reproduced in dimensions, and car flag versions are also sold. The flag is also available in dimension versions. The flag has become a celebratory symbol for Chicago Cubs fans who purchase reproductions and take them to games at home and on the road to show support. The fans wave them after victories at Wrigley Field, and they hang them in the stands during playoff series. Some fans fly a win flag in place of or in addition to the Flag of the United States on days when the Cubs win. Since 1998, the flags have become ever more popular with demand reaching a level where they are sold at Wrigley field. In seasons when the Cubs are performing poorly the tradition has led to parody and satire, such as stories of the Cubs retiring the win flag due to signs of neglect. While not having the popularity of the Win Flag, the Loss Flag has become increasingly popular with clubs who traditionally have rivalries with the Cubs (such as the St. Louis Cardinals or Chicago White Sox). Fans of those teams wave the blue flag after their team defeats the Cubs at Busch Stadium or Sox Park. Organizations such as the "Cubs Suck Club" provide links to download Loss Flags for printing and instructions on how to make printed flags more durable.
The flag is known by many names, with none being more prevalent that the rest, and may often be referred to by more than one name by the same manufacturer. Chicago Cubs W Win Flag is the name used on Amazon.com, however the company also refers to the flag as Chicago Cubs 'W' Banner Flag in their marketplace section. CubWorld.com also refers to the flag by the name Chicago Cubs 'W' Banner Flag. Other retailers use the names Cubs Win W Flag, Chicago Cubs Win 3' x 5' Flag, Cubs W Flag, or (Chicago Cubs) W Flag in the case of Sports Fan Warehouse. One retailer even sells an item called the Chicago Cubs W Fan Banner. Another retailer sells two versions of the flag listed as Chicago Cubs Win W Flag and Chicago Cubs Win Flag, yet its advertisements mentions celebrating a Cub win with the Chiacgo Cubs White "W" Flag. An alternate version that has the Chicago Cubs logo beneath the W can be found under the name Chicago Cubs Win W Banner.
The flags were originally a white "W" on a blue flag and a blue "L" on a white flag. Ernie Banks was the first Cub to have his number retired on August 22, 1982, and his number 14 has been flown in blue on a white flag (echoing the pattern of a Cubs home uniform shirt) on the left field foul pole ever since. On August 13, 1987, Billy Williams had his number retired and it flew with the same color scheme, on the right field foul pole. The scheme of the Cubs Win flag was reversed in the early 1980s. The change in the flag color scheme matched the Win flag color with the honored colors of the retired number flags. Subsequent retired Cubs numbers for Ron Santo and Ryne Sandberg also match this color scheme.
In addition to the flags, Wrigley authorized Bill Veeck, the leader of the bleacher reconstruction project, to add colored lights on the crossbar of the masthead so that the Chicago 'L' passengers would be able to see the outcome of Cubs home games after sunset. In his autobiography, Veeck remembered the colors as green for a win and red for a loss. Hartell's book acknowledges Veeck's comments, but reports that contemporary newspapers stated that the colors of the lights were blue and white, as they are now. Eventually the original lights on the masthead were replaced by lights directly on the top of scoreboard, still visible from outside Wrigley field. The lights complement the flags by helping night time passersby learn the result of that day's Cubs game at a glance. The current blue and white Win/Loss lights were added atop the scoreboard in 1978.
On April 23, 2008 the Cubs won for the 10,000th time in the history of the franchise on the road against the Colorado Rockies. Like the 9,000th win, the 10,000th win came in a 7–6 victory at Coors Field. The Cubs were the second franchise to achieve 10,000 regular season wins; the San Francisco Giants/New York Giants were the first. The franchise flew a special 10,000th win flag along with a Cubs Win flag to commemorate the landmark achievement for the franchise. This was unusual not just for the 10,000th win, but also for flying the flag in reference to a road game. The special flag flew from the afternoon of April 24, 2008 until immediately prior to the next home game on April 29, 2008 at 19:05 against the Milwaukee Brewers. After the flag was taken down, it was autographed by all members of the 2008 Chicago Cubs and auctioned off for charity.