What is Eid al-Adha?

Eid al-Adha is one of the two major festivals in Islam, also known as Eid al-Adha. This festival is after Eid al-Fitr. On Eid al-Adha, male Muslim compatriots got together with the learned imam very early, and began to slaughter cattle and sheep after the distance ended. Before slaughtering cattle and sheep, they should get together and explain the purpose of the cattle and sheep you want to slaughter! There is another story about this, I don't remember it clearly. It is said that a long time ago, Allah wanted to test Sheng (the content of the test was not very clear). Behind; Behind ............................, Mu Sheng used his son to slaughter. However, a black-headed sheep appeared in the sky and replaced Musheng's son with Yang, so Eid al-Adha came. However, there are many explanations about the source of this, and I don't remember it clearly!