Final answer:
The Janissaries served as palace attendants and household guards to the Sultan, and some also became administrators or soldiers. They wielded considerable political and military power within the Ottoman Empire.
Step-by-step explanation:
Many Janissaries became palace attendants or household guards to the Sultan, while others held positions like administrators or soldiers. As part of the elite corps of the Ottoman army, the Janissaries were crucial in military engagements and had significant political power due to their direct service to the Sultan. Over time, the Janissaries gained enough power to challenge and change rules, such as those prohibiting them from marrying or owning property, and they held distinct cultural influences, such as with their own form of music, mehterân.