Sometimes the person (often called a legate) would be empowered in a general sense to speak for the prince in all matters and to bind him to agreements. In other cases, the legate had restricted powers that were explicitly laid out in a letter of commission.
The legate had no special status. If the two powers were at war, the legate could only trust in the other prince's safe conduct, which was not always honored. Sometimes the delegation would comprise many men and would take months or more to complete its work, but it was never a permanent arrangement.
After the Peace of Lodi (1454) the Italians began general use of the resident ambassador. This person had protected legal status, with his residence being in a sense his native soil. His duty was not only to negotiate, but to keep up a constant stream of reports to his homeland.
Venice is most noted among the Italians. Elsewhere, Louis XI of France and Ferdinand of Spain made excellent use of ambassadors to further their political designs. By the middle of the 16th century, most European states with international concerns had ambassadors at other capitals.