"Good day" is a standard greeting used in English-speaking countries. However, there are many synonyms that you can use to express the same sentiment. For example, you could say "hello," "hi," "good morning," "good afternoon," or "greetings." If you want to be a bit more formal, you could also use phrases like "how do you do" or "pleased to meet you." Additionally, some people might use regional or cultural terms, such as "bonjour" in French-speaking areas or "aloha" in Hawaii. Whatever phrase you choose, the goal is to express warmth and positivity as you greet others and begin your interactions for the day.