Alex(played by Selena Gomez) is the middle child of the three Russo children born to Jerry & Theresa Russo. All three children are half-wizards untill the time of they all participate in the family wizard competition, in which only one will keep their powers while the other siblings will have their powers transfered to the winner, granting them "Full wizard" powers.
Alex, however, is a bit of a rule-breaking teen bad girl, always getting into trouble and trying to find the easy way out of things. She's not too book smart, but pretty streetwise, which has helped her not only get into trouble, but out of it as well[usually after making the trouble worse].
When we first meet her, she's 14... but now in it's 4th season, she's 17 going on 18.