An “ambassador” is a person who represents one country—in another one.
For instance, Canada has ambassadors in many countries around the world. They are high ranking diplomats who represent their country. They typically work from offices called embassies.
The U.S. has many ambassadors stationed around the world, representing the United States.
The U.S. has an embassy in Libya, in Northern Africa.
Libya has been in the news this year because it was part of the Arab Spring, in which some countries’ people protested against corrupt governments.
On Wednesday, the U.S. ambassador to Libya and three embassy staff were killed.
Facts are still emerging about the incident—about why it happened and what the U.S. reaction to it will be.