interjection
A warm greeting used when welcoming someone to a place, event, or group. Often used in set phrases like ようこそ日本へ (Welcome to Japan).
ようこそ、私たちの家へ。
Welcome to our home.
ようこそお越しくださいました。
Thank you for coming; welcome.
いらっしゃい is a more casual welcome, often used in shops or when greeting guests at the door. ようこそ is slightly more formal and often used in speeches or written messages.
Derived from the adverb よく (well) and the emphatic particle こそ. Originally meant 'indeed well (that you came)', and became a fixed greeting.