May the blessings of the Most Merciful God fill your life with peace, love and happiness.
The Islamic calendar has two major Eid festivals, Eid al-Fitr and Eid al-Adha. Eid al-Fitr comes at the end of Ramadan, a time of celebration after a period of fasting and Eid al-Adha (the Festival of Sacrifice) is a festival of commitment and obedience to Allah.
The Eid Mubarak greeting can be applied on both Eid al-Fitr and Eid al-Adha.
More info about Eid [theeid]