A school motto is a phrase, often Latin, that summarizes an educational institute's values and priorities. It is traditionally accompanied by a coat of arms.
Sometimes these mottos are not formally decided upon, but rather enter common usage over time. The two mottos of Eton, for example, the exclusive British public (private) school, are both described as "unofficial creations that, over time, have stuck." They are "Floreat Etona", which means "May Eton flourish," and "Esto perpetua, which means "May it last forever."
Universities often also have mottos. That of the University of Southern California (USC) is "Palmam Qui Meruit Ferat," which means "Let whoever earns the palm bear it." This is a classical allusion to signs of accomplishment and prowess.