Its unwanted. Usually people that pick on others has a lot of insecurities and/or have family problems. Their self esteem is low and they think making other people feel bad about theirselves will bring their esteem up.
Most bullying happens over the internet, on social media. Cyber bullying is more popular in modern day. Over facebook, Instagram, Twitter, etc. Kids these days are mean, they try to find just about anything wrong with one another, and once they find something, they take it and run with it. It hurts innocent children, sometimes so bad that they commit suicide.
Bullying is never the answer. People should really think about the outcome in everything they say before it reaches their lips. One little sentence that may seem nothing to you, may cost a whole life.