Answer:
They are Eid-ul-Fitr and Eid-ul-Adha. Eid-ul-Fitr celebrates the end of the month of Ramadan. Ramadan is when Muslims fast from sunup to sundown all that month.
Eid-ul-Adha commemorates the obedience shown when prophet Abraham PBUH submitted to a test from God commanding him to slaughter prophet Ishmael PBUH; then God gave a ram to slaughter instead. So we now butcher a ram and distribute the meat between us, our family, and the poor.