A tutor is a person who teaches or guides another person. Usually, the tutor is an older expert who teaches a younger learner. Early examples were Socrates, who taught philosophy by holding conversations with his students, and Aristotle, who was appointed the personal tutor of Alexander the Great when the latter was a youth.

The essence of a tutor's work is to adjust the teaching to the individual learner. The tutor has to take account of:

1. what the learner already knows and does not know
2. what the learner has incorrectly learnt
3. the personal interests and goals of the learner
4. the particular talents of the learner