A Jew is someone who believes in the Jewish faith or has a cultural connection to Judaism. If your parents are Jewish, you're likely to describe yourself as a Jew.
If you're a Jew, you most likely share a religious and ethnic background with other Jewish people. While some people convert to Judaism, most Jews trace their heritage back to common ancestors. Observant Jews worship on Saturdays and celebrate many holidays throughout the year. The Greek root of the word Jew is Ioudaios, from Aramic and Hebrew. The Hebrew word for Jew, y'hudi, comes from the name Y'hudah, or Judah.