The leader of a local Islamic community, particularly as practiced among Sunni Muslims. Not to be confused with the person who leads a congregational prayer (see: imam-al-jamaah) or the appointed leader of the Islamic world as understood by Shi'ite Imamah (see: shia-imam)
Common in established Sunni communities, the Imam Khatib is normally appointed to or elected by a local community and/or masjid. The term "Imam Khatib" is so used because he regularly fulfills the roles of both "Imam" (leader of prayer) and "Khatib" (preacher who delivers the sermon during the Friday and Eid prayers).
In addition to the dual roles mentioned above, he also acts as a general spiritual advisor for local Muslims.
For further details, refer to the following Wikipedia page:
The use of this tag is specifically for those questions regarding the position itself, including questions particular to Muslims about living under the jurisdiction of one; if the question is explicitly about or for the person who is leading a congregational prayer (whether or not they're an established "Imam Khatib") please use the related tag imam-al-jamaah.
Note: This is not to be confused with the Shi'ite understanding of the term "Imam," which has a very particular meaning under the principles of Imamah; for such questions refer to the tag shia-imam instead.