Definition:
An attendant or employee, usually in uniform, who carries messages, ushers guests, runs errands, etc.; a person employed by a legislature to carry messages and run errands for the members, as in the U.S. Congress.
During a MUN conference, pages(some call them "ushers") help pass messages between delegates within a committee, as well as send messages to delegates in other committees. As introduced in the previous word, delegates may ask pages to help pass notes to the dais to be put on the speaker's list. In the United Nations, this is especially helpful when a delegate in a committee wants to get information to their ambassador in the General Assembly regarding a resolution that is being sent to the Assembly for discussion.
Examples:
There are no direct dialogues in a MUN conference; pages(ushers) may help pass notes in between.
Pages also are responsible for sending the documents for print and distributing them to all delegates.
I beckoned for the page to pick up my note and pass it to the Delegate of Gambia.