When to use welcome?

Hello there! I'm curious about something related to the phrase "When to use welcome?" Could you perhaps elaborate on some scenarios where it would be appropriate to use the word "welcome"? For instance, are there any specific social situations or business interactions where expressing welcome is not only customary but also highly appreciated? Additionally, how does the tone and context in which "welcome" is used impact the overall message it conveys? I'd be grateful for your insights on this matter.