Qadar means that Allah has decreed everything that happens in the universe according to His prior knowledge and the dictates of His wisdom.

The belief that Allah knows all things, in general and in detail, from eternity to eternity, whether that has to do with His actions or the actions of His slaves.

The belief that Allah has written that in al-Lawh al-Mahfooz (the Book of Decrees).

The belief that whatever happens only happens by the will of Allah - whether that has to do with His actions or the actions of created beings.

Allah Almighty says concerning His actions (interpretation of the meaning):

"And your Lord creates whatsoever He wills and chooses" (Surah al-Qasas, 68).

The belief that all things that happen are created by Allah in their essence, their attributes and their movements.

Allah says (interpretation of the meaning):

"Allah is the Creator of all things, and He is the Wakeel (Trustee, Disposer of affairs, Guardian) over all things" (Surah al-Zumar, 62).