Each colour on the tharangaa/Indian flag represents a people. Kesri (orange) represents the Sikhs. The colors on the Indian flag weren't always in the order that they are in now. Kesri wasn't always at the top of the flag but thanks goes to Baba Kharag Singh Ji, they put forward the condition that whoever is on the frontline of the battle that was then being fought should have their color at the top of the flag. This condition was agreed upon and kesri was moved up to the top of the Indian flag. Sant Jarnail Singh Ji explains the story in this video.