Japanese are very dicipline where they will wish everyone whenever they meet in the morning, afternoon and night.

Good Morning – Ohayō Gozaimasu (おはようございます)
Good Afternoon – Konnichiwa (こんにちは)
Good Evening – Konbanwa (こんばんは)
Good Night – Oyasumi Nasai (おやすみなさい)

There is another type of wishes where Japanese family will normally say :
When you are going out from home, dormitory, office, etc
You should say : Itte Kimasu (いってきます)- I’m going out
They should reply : Itte Rasshai (いってらっしゃい)- Take care yourself

When you return home, office, dormitory, etc
You should say : Tadaima (ただいま)- I’m Home
They should reply : O Kaeri Nasai (おかえりなさい)- Welcome Back

Based on the above, you may notice that some word has a double character like “itte” & “rasshai”. This will happen whenever there is a small “tsu”.
Example : itte (いて)and rasshai (らしゃい)

To understanding further on the pronunciation, visit HERE