Free will is the freedom of self-determination and action independent of external causes. It is the ability to make choices. A choice is free if it is consistent with a person's desires and nature. Free will is of two main types: compatibilistic and libertarian.
Compatibilism is the position that man's free will is restricted by his sinful nature. And as a result, he can choose only what his sinful nature will allow him to choose, which means he will not choose God of his own free will because he is enslaved to sin. It also states that a person is only as free as his nature permits him to be free and that his sinfulness prevents him from freely choosing God (1 Cor. 2:14, Rom. 3:10-12, Rom. 6:14-20).
Libertarian free will is the position that man's free will is not restricted by his sinful nature in that he is not enslaved by sin so that he only chooses sinful things and that he can freely choose to accept or reject God despite his enslavement to sin. It also states that an unsaved sinner is still able to freely choose God in spite of his sinful nature (John 3:16, 3:36).