Зачем в сеттере используется this? Java

Есть код:

public class Book {
public void main(String[] args){
    Title title = new Title();
    Author author = new Author();
    Content content = new Content();
    title.setTitle("Bible");
    author.setAuthor("Jesus");
    content.setConetnt("Holy shit");
    title.show();
    author.show();
    content.show();
}
public class Title{
    public String title;
    public void setTitle (String title){
        this.title = title;
    }
    public String getTitle (){
        return title;
    }
    public void show (){
        System.out.println(title);
    }
}
public class Author{
    public String author;
    public void setAuthor (String author){
        this.author = author;
    }
    public String getAuthor (){
        return author;
    }
    public void show (){
        System.out.println(author);
    }
}
public class Content {
    public String conetnt;
    public void setConetnt (String conetnt){
        this.conetnt = conetnt;
    }
    public String getConetnt() {
        return conetnt;
    }
    public void show (){
        System.out.println(conetnt);
    }
}
}

Зачем здесь в методе set используется this?