An escort was a citizen of the Capitol whose main duty was to accompany the tributes of their assigned district and help them adjust with the guidelines of the Capitol. They had dozens of tasks assigned to them around the time of the annual Hunger Games.
Reapings and Victory Tour
Escorts had the honor of calling names for the Hunger Games by choosing names from the female and male reaping bowls. They were always excited for the Hunger Games on Reaping Day and were cheerful, wishing the children of the districts 'Happy Hunger Games, and may the odds be ever in your favor!' Due to their Capitol upbringing, they didn't understand how the people of the districts do not celebrate the Hunger Games and didn't realize how the districts truly feared the Hunger Games.
If the escort's tribute became a victor, the escort's job also included "escorting" the victor on the Victory Tour. After this, the escort could be promoted to a higher ranking district for the next year's Games, or they could choose to stay with the district that they were with previously. Effie Trinket once stated that she wished to be bumped up to a better District where they had real victors.
The only named escort is Effie Trinket, who worked as an escort for some time up to and including the 75th Hunger Games. Effie Trinket is a kind and peppy escort who cared for tributes Katniss Everdeen and Peeta Mellark while they stayed in the Capitol before the Hunger Games started, as well as on the 74th Victory Tour.
She would always make announcements and schedule to prepare and get ready for the day ahead of them. Although Effie cared about her tributes, she never had high hopes for any tributes from District 12 surviving due to their poor living conditions. Effie has very good manners and encourages others to work on them as well, including Katniss.
However, she is somewhat blind to the conditions of those in the districts, shown when she complained about the table manners of a pair of starving children.