Custom Pennants have been around since the 19th century ever since the baseball league was formed. They needed something to specify the teams and a kind of memorabilia that could be exchanged between competitive teams before a sporting event, or a game. These became very popular and were used amongst military purposes as well as sports. Also, special clubs or charity groups used pennants to originate their logo or colours.
Pennants became very popular in Europe and other parts of the world. Many soccer teams use their custom pennants and exchange them during competitions. Most college basketball and college football teams used pennants. In America, the custom pennants are mostly longer horizontally and shorter vertically but they are still in the shape of a triangle. In Europe sportsmen use pennants which are more compact. Of course, all teams or clubs have copyrights for their logos and colours. It is illegal to duplicate or produce the logo of a club, without their permission.
Club merchandising is a big market these days and of course every club wants to create a good profit for their merchandise. They use their own producers or manufacturers and then they use their own marketing to sell their merchandise. You may come across illegally produced flags with dodgy logos. Sometimes these logos are partly different because of the copyright reasons. It’s best to buy official merchandise. This way, the club makes money from their logo or brand or colours.
Before every football game, the team captains always exchanges their custom pennants during coin toss. This is a tradition, in all of the football leagues. After that, these pennants are always kept or displayed in the club premises. They are almost like historical artefacts. On such and such day, so and so teams have competed for such league. And all of them get kept. Otherwise, why all these captains will go through all that trouble?