They are more than old but familiar catchy sayings. They are brief and memorable expressions of popular wisdom. A better definition is given by Mieder who defines a proverb as "a short, generally known sentence of the folk which contains wisdom, truth, morals, and traditional views in a metaphorical, fixed and memorizable form and which is handed down from generation to generation."
They teach us wisdom and truth. They are the knowledge passed down for centuries across generations.
Some examples of proverbs include the following: curiosity killed the cat, a lie has no legs, devil lies in the details, honesty is the best policy, hunger is the best sauce, and don't cry over spilled milk.
Proverbs are useful and powerful, but are not without faults. In particular, they should not be considered as absolute truths. They help ESL students to understand the English culture, mindset, and way of life.