Here's why Padawans wear a single braid before they become a Jedi in Star Wars. The George Lucas-created franchise lore is rich and vibrant, with great time and attention put into the smallest details which fans love obsessing about. Among the most interesting - and arguably the most popular - aspect of Star Wars is the Jedi and how their order works.
There's a wealth of topics to discuss about the Jedi - from their origins to their code, Star Wars has explored all these things in varying degrees and across different media. While the original Star Wars trilogy didn't fully expound on the idea of a group of powerful Force-users, the prequels gave fans a better idea of who they are and how they function. Using their ability to tap into the Force, the Jedi are tasked to be the protectors of peace and order in Star Wars. They're never meant to attack or kill, which is one of their most distinct qualities from the Sith. As the franchise revealed the origins of Darth Vader as Anakin Skywalker (Hayden Christensen), fans also learned about how people are chosen to join the Jedi.
Being part of the Jedi Order is no easy task, and having a strong connection to the Force doesn't fast-track one's journey, as proven by Anakin's arc. Each potential member has to go through the training from the Jedi Academy and be mentored by a Jedi Master. Obi-Wan Kenobi (Ewan McGregor) and Anakin were separately depicted as Padawans in the prequels - the former in Star Wars: Episode I - The Phantom Menace, and the latter in Star Wars: Episode II - Attack of the Clones. During their respective times as a Padawan, they both sported a single braided hair that disappeared once they graduated and became Jedi Knight.
Known as the Padawan braid, species who are training to become Jedis (and have hair or fur) grow a lone tight long braid behind their right ear. It's worth noting that in the prequels, Obi-Wan and Anakin's braids tend to change sides, which is likely due to footage manipulation during post-production. Padawans can be creative with their locks to differentiate themselves from their peers like weaving a ribbon or other accessories into it. Aside from the aesthetic of it, there's actually a function to the Padawan braid - it helps to easily identify one's rank in the Jedi Order.
When a Padawan finishes his/her training and becomes a Jedi Knight, the braid is cut using their lightsaber. Meanwhile, if one fails to finish the course or leave the Jedi Order in the middle of their training for any reason, the lock is ripped off instead; this was what happened when Ahsoka Tano decided to walk away from the academy. Those who can't grow hair can tie a lock in their wrist or other parts of their body, or do other modifications like wearing a piercing or markings.
Unlike Princess Leia's (Carrie Fisher) iconic hair buns from the original Star Wars film, there doesn't seem to be any real-life inspiration for the Padawan braid. Instead, it was simply a cool character design choice from Lucas and his team. Chronologically, the Padawan braid has not been seen since the prequel films, but perhaps we'll see it again as Din Djarin searches for the remnants of the Jedi in the upcoming season of The Mandalorian.