"Hey" is a casual greeting commonly used in English-speaking countries. It serves as a friendly way to acknowledge someone or initiate a conversation. The word can be used in various contexts, from informal chats among friends to more relaxed professional settings. In addition to being a greeting, "Hey" can also express attention or surprise. For example, someone might say "Hey!" to get another person's focus or to react to something unexpected. This versatility makes "Hey" a popular choice in everyday communication, especially in text messages and social media interactions.