Who were the witches in 'Macbeth'?

In the Shakespearean play 'Macbeth', the characters included mortal and supernatural beings. Among the supernaturals were witches. The supervisor of the witches was Hecate, who gave her exact position description as 'mistress of your charms' and 'close contriver of all harms' [Act 3 Scene 5 Lines 6-7]. Her employees were the three witches whom Macbeth [c. 1014-August 15, 1057] called the Weird Sisters [Act 3 Scene 5 Line 133; Act 4 Scene 1 Line 136].

They plot mischief against Macbeth using charms spells and prophecies their predictions prompt him to murder duncan to order the death of banquo and his sons and to blindly believe in his own immortality . the play leaves the witches unclear true nature we don't know if they make their prophecies come true or where they get their knowledge from.
Hecate