The Congressionally mandated Diversity Immigrant Visa Program makes 50,000 greencards available per year to citizens from countries with low rates of immigration to the US in previous years. These 50.000 immigrant visas are allocated through a lottery that is held once a year.
All information required on how to enter the lottery can be found on the website of the Department of State. Registration for the green card lottery (usually in October) is free and very simple. Entrants can check on the same website whether or not they have been selected in May of the following year.
The Greencard lottery is free!
Some organizations offer assistance in applying for the lottery in exchange for a fee, and promise higher success rates. The Department of State warns against these organizations. Participation in the greencard lottery is very simple and does not require any paid help. Read the Fraud Warning on the website of the Department of State for more information.