"Thee" is considered Old English, which was used a long time ago. It is not used in normal modern-day conversation. "Thee" is an object pronoun, similar to "thou", which is a subject pronoun. Thou art mine enemy = You are my enemy Speak thy name = Speak your name I say to thee, come hither = I say to you, come here

"Thee" is older English, but over time the plural "you" replaced the singular "thou". "Thou/thee/thy/thine" (related to "I/me/my/mine") is now only seen in old texts and poetry. I love thee. / Thou lovest me. (Oops.. yes, verbs changed in Shakespeare's time as well)

Thee is early modern english, thee comes from older conventions that have since been dropped from the english language.