Aisatsu - Greetings

Konnichiwa - Hello/Good Afternoon
Ohayou gozaimasu - Good morning (formal)
Ohayou - Good Morning (informal)
Konbanwa - Good Evening
O genki desu ka? - Are you well (how are you?)
Hai, Genki desu. - Yes, I am well.

Sayounara - Good - bye
Jaa ne - See you later!
Mata ne - Until next time!
Bai bai - Bye bye!
Mata ashita - Until tomorrow!

Here is a video on aisatsu, or Japanese greetings: