The two main religious festivals in the Islamic calendar are:
Eid-ul-Fitr
This festival marks the end of Ramadan (the fasting period).
Families get together for a feast and often children receive money or gifts.
It is a big celebration and a public holiday in Muslim countries.
Eid-ul-Adha
This festival marks the end of Hajj.
Muslims also believe that the Prophet Abraham (one of God's messengers) was going to sacrifice his son because that is what Allah had told him to do.
This was a test to see Abraham's obedience and Allah told him to slaughter a goat instead.
Often Muslims slaughter animals to remember this sacrifice.