Greetings

Japanese greetings depend on the time of day.

• おはようございます (ohayō gozaimasu) — good morning. Drop ございます with friends: おはよう.
• こんにちは (konnichiwa) — hello / good afternoon. The final は is pronounced wa — it comes from the topic particle.
• こんばんは (konbanwa) — good evening. Same rule: the は is read wa.

Three survival phrases you will use every single day:

• ありがとうございます — thank you (polite).
• すみません — excuse me / sorry. Also the magic word to call a waiter or ask a stranger something.
• さようなら — goodbye (a bit formal; friends usually say じゃあね).

And the simplest pair: はい (yes) and いいえ (no).