It is common to use a special greeting used just for that occasion on special days, holidays and other special occasions. Here are some of the most common:

Birthdays

Happy birthday!
Best wishes / Good luck on your thirtieth (age - use an ordinal number) birthday!
Many happy returns!

Wedding / Anniversary

Congratulations!
Best wishes / good luck on your tenth (number - use an ordinal number) anniversary!
Here's to many more happy years together (used when making a toast)

Special Holidays

Merry Christmas!
Happy New Year / Easter / Hanukkah / Ramadan etc.
All the best for a happy New Year / Easter / Hanukkah / Ramadan etc.

When making special greetings to children on their birthday and at Christmas, it is also common to ask them what they received:

Merry Christmas! What did you get from Santa Claus?
Happy Birthday! What did your Daddy get for you?

Special Occasions

Congratulations on your promotion!
All the best for your ...
I'm so proud of you!

By Kenneth Beare, About.com Guide

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