The Bulletin Boards interview questions

1.what is seo ? and its 3 types 2.Difference between index vs crawling? 3.what is blacklink and why it is important? 3.what is difference between copywriting and content writing? 4.5 methods of doing off page seo 5. what is on page seo , name some of it's techniques? 6.why seo is better than ppc?