Hector writes, "Because I was arrested for a crime in the US, I was convicted, and due to my unlawful status in America, I was also deported with a ten-year ban. Now it has already been more than ten years and I would like to apply for a visitor's visa to visit old friends. What should I do?"
Receiving a visa to the United States is a privilege and depends entirely at the discretion of the officer handling your application. Since you broke the law and were also living in the country illegally, while the ban was only 10 years, chances are that the officer will suspect that you are likely to not depart after your period of stay is over and/or commit more crimes. Having said that, if you have the money to pay the fees, you should apply for a visa, and see what happens. If you are in a country where visas require interviews, you will have an opportunity to explain why you are a different man. For example, you can bring evidence of education that you have completed or jobs that you have held, and maybe a police report indicating that you have not committed in any crimes in your country to prove that you are now a good man and regret your mistakes from the past. The worst that can happen is that your application will be denied.