Meaning of mappedBy attribute in an annotation?

I'm a novice in hibernate. I was trying to create a one-to-one mapping between Person and PersonDetail entity in the following code:

@Entity
public class Person {

    private int personId;
    private String personName;
    private PersonDetail personDetail;

    @OneToOne(mappedBy="person")
    public PersonDetail getPersonDetail() {
        return personDetail;
    }

    public void setPersonDetail(PersonDetail personDetail) {
        this.personDetail = personDetail;
    }

    @Id
    @GeneratedValue
    public int getPersonId() {
        return personId;
    }

    public void setPersonId(int personId) {
        this.personId = personId;
    }

    public String getPersonName() {
        return personName;
    }

    public void setPersonName(String personName) {
        this.personName = personName;
    }
}


@Entity
public class PersonDetail {

    private int personDetailId;
    private String zipCode;
    private String job;
    private double income;

    private Person person;

    @OneToOne(cascade=CascadeType.ALL, fetch=FetchType.EAGER)
    public Person getPerson() {
        return person;
    }

    public void setPerson(Person person) {
        this.person = person;
    }

    @Id
    @GeneratedValue
    public int getPersonDetailId() {
        return personDetailId;
    }

    public void setPersonDetailId(int personDetailId) {
        this.personDetailId = personDetailId;
    }

    public String getZipCode() {
        return zipCode;
    }

    public void setZipCode(String zipCode) {
        this.zipCode = zipCode;
    }

    public String getJob() {
        return job;
    }

    public void setJob(String job) {
        this.job = job;
    }

    public double getIncome() {
        return income;
    }

    public void setIncome(double income) {
        this.income = income;
    }

}

I want that PersonDetail should be the owning entity (I know that vice versa is correct, but I just want to test). What I do