Probably the most obvious characteristic of a Witch was the ability to cast a spell.
A spell being the word used to signify the means employed to carry out a magical action.
A spell could consist of a set of words, a formula or verse, or a ritual action, or any combination of these.
Spells traditionally were cast by many methods.
Such as by the inscription of runes or sigils on an object to give it magical powers.
By the immolation or binding of a wax or clay image of a person to affect him or her magically.
By the recitation of incantations.
By the performance of physical rituals,
By the employment of magical herbs as amulets or potions.
By gazing at mirrors, swords, or other specula (scrying) for purposes of divination,
As well as by many other means.