"Yo" is a casual greeting commonly used in informal settings, particularly in the United States. It is often used among friends or peers to grab attention or initiate conversation. The term has roots in various cultures and has evolved over time, becoming a staple in youth slang. In addition to being a greeting, "Yo" can also express excitement or surprise. It is frequently used in music, especially in genres like hip-hop and rap, where artists incorporate it into their lyrics to create a relatable and engaging vibe.