How is an imam chosen?An imam is selected at the community level. Members of the community choose someone who is considered knowledgeable and wise. The imam should know and understand the Quran, and be able to recite it correctly and nicely. The imam is a respected member of the community. In some communities, an imam may be specifically recruited and hired, and may have undergone some special training. In other (smaller) cities, imams are often chosen from among the existing members of the Muslim community. There is no universal governing body to supervise imams; this is done at the community level.
What does an imam do?
For each of the five daily prayers, the imam is present at the mosque to lead the prayers. On Friday, the imam usually delivers the khutba (sermon). The imam also leads the taraweeh (nightly prayers during Ramadan), either alone or with a partner to share the duty. The imam also leads all other special prayers, such as for funerals, prayers for rain, prayers during an eclipse, and more.
What other role does an imam serve in the community?In addition to being a prayer leader, the imam may also serve as a member of the larger leadership team in a Muslim community. As a respected member of the community, the imam's counseling may be sought in personal or religious issues. One may ask him for spiritual advice, help with a family issue, or in other times of need. The imam may be involved in visiting the sick, engaging in inter-faith service programs, officiating marriages, and organizing educational gatherings in the mosque. In modern times, the imam is increasingly in a position to educate and reform youth away from radical or extremist viewpoints. Imams reach out to youth, inspire them in peaceful pursuits, and teach them the correct understanding of Islam -- in the hopes that they will not fall prey to misguided teachings and resort to violence.
So, an imam is a member of clergy?No, there is no clergy in Islam. Muslims believe in a direct connection with the Almighty, without need of an intercessor. The imam is simply a leadership position, for which someone is hired or selected from among the community members. A full-time imam may undergo special training, but this is not required. There is no universal governing body to supervise imams; this is done at the community level.
The word "imam" can also be used in a broader sense, referring to any person who leads prayer. So in a group of young people, for example, one of them may volunteer or be selected to be the "imam" for that prayer (meaning, he or she will lead the others in prayer).
Among Shia Muslims, the concept of an imam takes on a more central clerical position. They believe that their specific imams were chosen by God to be perfect examples for the faithful. They must be followed, since they were appointed by God and are free from sin. This belief is rejected by the majority of Muslims (Sunni).